Document:

Exhibit 10.1

 

STOCKHOLDER SUPPORT AGREEMENT

 

This Stockholder Support Agreement
(this “Agreement”) is dated as of November 30, 2021, by and among Atlantic Coastal Acquisition Corp., a Delaware corporation
(“ACAH”), the Persons set forth on Schedule I attached hereto (each, a “Company Stockholder”
and, collectively, the “Company Stockholders”), and Essentium, Inc., a Delaware corporation (the “Company”).
Capitalized terms used but not defined herein shall have the respective meanings ascribed to such terms in the Business Combination Agreement
(as defined below).

 

RECITALS

 

WHEREAS, as of the date hereof,
each Company Stockholder is the holder of record and the Beneficial Owner of, and has voting power (including, without limitation, by
proxy or power of attorney) and dispositive power over, such number of Company Shares and Company Convertible Securities as are indicated
opposite such Company Stockholder’s name on Schedule I attached hereto (such Company Shares, the “Existing Subject
Shares” and such Company Convertible Securities, the “Existing Subject Securities”);

 

WHEREAS, contemporaneously with
the execution and delivery of this Agreement, ACAH, Alpha Merger Sub 1, Inc., a Delaware corporation and a wholly owned Subsidiary of
ACAH (“Merger Sub”), and the Company entered into a Business Combination Agreement (as amended or modified from time
to time, the “Business Combination Agreement”) pursuant to which, Merger Sub will merge with and into the Company (the
 “Merger” and, together with the other transactions contemplated by the Business Combination Agreement, the “Transactions”),
with the Company surviving the Merger as a wholly-owned subsidiary of ACAH; and

 

WHEREAS, as a material condition
and inducement to ACAH and the Company to enter into the Business Combination Agreement and to consummate the transactions contemplated
therein, the Company Stockholders have agreed to enter into this Agreement with respect to all of the Subject Securities and the parties
hereto desire to agree to certain matters as set forth herein.

 

AGREEMENT

 

NOW, THEREFORE, in consideration
of the premises and the mutual promises set forth herein and for other good and valuable consideration, the receipt and sufficiency of
which are hereby acknowledged, the parties hereto, each intending to be legally bound, hereby agree as follows:

 

     

     

    

 

ARTICLE
I

General

 

Section 1.1           
Definitions. As used in this Agreement, the following terms have the respective meanings set forth below.

 

“Beneficial Owner”
shall be interpreted in accordance with the term “beneficial owner” as defined in Rule 13d-3 adopted by the SEC under the
Exchange Act; provided that, notwithstanding the generality of the foregoing, for purposes of determining Beneficial Ownership,
a Person shall be deemed to be the Beneficial Owner of any securities which such Person has the right to acquire pursuant to any agreement,
arrangement or understanding or upon the exercise of conversion rights, exchange rights, warrants or options, or otherwise (irrespective
of whether the right to acquire such securities is exercisable immediately or only after the passage of time, including the passage of
time in excess of sixty (60) days, the satisfaction of any conditions, the occurrence of any event or any combination of the foregoing).
The terms “Beneficial Ownership,” “Beneficially Own” and “Beneficially Owned” shall have a correlative
meaning.

 

“Company Shares”
shall have the meaning set forth in the Business Combination Agreement.

 

“Company Convertible
Securities” shall have the meaning set forth in the Business Combination Agreement.

 

“Subject Securities”
means, with respect to a Company Stockholder, (a) the Subject Shares, and (b) the Existing Subject Securities of such Company Stockholder,
together with any Company Convertible Securities of which ownership of (i) record and Beneficial Ownership, or (ii) any dispositive power,
is hereafter acquired by such Company Stockholder during the Term.

 

“Subject Shares”
means, with respect to a Company Stockholder, the Existing Subject Shares of such Company Stockholder, together with any Company Shares
of which ownership of (i) record and Beneficial Ownership, (ii) the power to vote (including, without limitation, by proxy or power of
attorney) or (iii) any dispositive power, is hereafter acquired by such Company Stockholder during the Term.

 

“Term”
shall mean the period commencing on the date of this Agreement and ending on the Expiration Time.

 

“Transfer”
means, directly or indirectly, to (i) sell, offer to sell, contract or otherwise agree to sell, transfer, convey, exchange, assign, deposit,
hypothecate, loan, pledge, encumber (including creating or incurring any Lien upon), grant any option to purchase or otherwise dispose
of or agree to dispose of (including by gift, merger, consolidation by operation of Law or otherwise (including by conversion into securities
or other consideration), either voluntarily or involuntarily, or by tendering into any tender or exchange offer), file (or participate
in the filing of) a registration statement with the SEC (other than the Registration Statement / Proxy Statement) or establish or increase
a put equivalent position or liquidate or decrease a call equivalent position within the meaning of Section 16 of the Exchange Act, with
respect to any Subject Securities (or any security convertible or exchangeable into Subject Shares), (ii) enter into any swap or other
arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of any Subject Securities (or
any security convertible or exchangeable into Subject Shares), or (iii) enter into any contract, option or other arrangement or understanding,
directly or indirectly, to take any of the foregoing actions.

 

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ARTICLE
II

stockholder SUPPORT AGREEMENT; COVENANTS

 

Section 2.1           
No Transfer. During the Term, each Company Stockholder shall not, and shall cause each of its Affiliates not to, (a) Transfer
any of the Subject Securities or any other interest specifically therein (including by tendering into any tender or exchange offer by
any Person other than ACAH or any of its Subsidiaries), (b) publicly announce any intention to effect any Transfer, (c) enter into any
agreement, arrangement or understanding, directly or indirectly, with any Person (other than ACAH or Merger Sub), or take any other action
that would prevent or disable such Company Stockholder from performing his, her or its obligations under this Agreement, (d) deposit any
of the Subject Securities into a voting trust, enter into any agreement, arrangement or understanding with any Person to vote or give
instructions inconsistent with this Agreement, enter into any voting agreement or arrangement with respect to such Company Stockholder’s
Subject Securities, or grant any proxy (except as otherwise provided herein) or power of attorney with respect thereto, or (e) commit
or agree, directly or indirectly, to take any of the foregoing actions. Nothing herein shall prohibit a Transfer to an Affiliate of a
Company Stockholder (a “Permitted Transfer”); provided, that any Permitted Transfer shall be permitted only
if, as a precondition to such Transfer, the transferee also agrees in writing to assume all of the obligations of such Company Stockholder
under, and be bound by all of the terms of, this Agreement; provided, further, that any Transfer permitted under this Section
2.1 shall not relieve a Company Stockholder of its obligations under this Agreement. Any Transfer in violation of this Section
2.1 with respect to a Company Stockholder’s Subject Securities shall be null and void ab initio. Nothing in this Agreement
shall prohibit direct or indirect transfers of equity or other interests in a Company Stockholder.

 

Section 2.2           
New Securities. In the event that, during the Term, (a) any Subject Securities are issued to a Company Stockholder after
the date of this Agreement pursuant to any stock dividend or distribution, stock split, recapitalization, reclassification, combination
or exchange of Subject Securities or otherwise, (b) a Company Stockholder purchases or otherwise acquires Beneficial Ownership of any
Subject Securities or (c) a Company Stockholder acquires the right to vote or share in the voting of any Subject Securities (clauses (a),
(b) and (c), collectively, the “New Securities”), then such New Securities acquired or purchased by such Company Stockholder
shall be subject to the terms of this Agreement to the same extent as if they constituted the Subject Securities owned by such Company
Stockholder as of the date hereof. Each Company Stockholder hereby agrees to notify ACAH and the Company in writing as promptly as practicable
of any acquisition of New Securities.

 

Section 2.3           
Agreement to Vote. During the Term of this Agreement, each Company Stockholder hereby unconditionally and irrevocably agrees
that (a) at any meeting of the stockholders of the Company (including any adjournment or postponement thereof), however called, (b) in
any action by written consent of the stockholders of the Company requested by the Board of Directors of the Company or otherwise undertaken
in connection with the Transactions (which written consent shall be delivered promptly, and in any event within two (2) Business Days,
after the Registration Statement / Proxy Statement (as contemplated by the Business Combination Agreement) has been declared effective
and has been delivered or otherwise made available to the stockholders of ACAH and the Company), and (c) in any other circumstance upon
which a vote, consent or other approval of the stockholders of the Company is sought, such Company Stockholder shall, if a meeting is
held, appear at the meeting, in person or by proxy, or otherwise cause its Subject Shares to be counted as present thereat for purposes
of establishing a quorum, and such Company Stockholder shall vote or provide consent or approval (or cause to be voted or consented or
approved), in person or by proxy, all of its Subject Shares:

 

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(a)         
to approve and adopt the Business Combination Agreement and the Transactions;

 

(b)         
to convert each Company Preferred Share into one Company Common Share prior to the Effective Time in accordance with the Business
Combination Agreement (after giving effect to the conversion of all Company Convertible Securities held by such Company Stockholder);

 

(c)         
in any other circumstances upon which a consent or other approval is required under the Company’s Governing Documents or
the Company Stockholders Agreements or otherwise sought with respect to the Business Combination Agreement or the Transactions, to vote,
consent or approve (or cause to be voted, consented or approved) all of such Company Stockholder’s Subject Shares held at such time
in favor thereof;

 

(d)         
to approve and adopt any proposal to adjourn or postpone such meeting of the stockholders of the Company to a later date if there
are not sufficient votes to adopt the Merger Agreement and/or if there are not sufficient shares present in person or by proxy at such
meeting of the stockholders of the Company to constitute a quorum;

 

(e)         
against and withhold consent with respect to any merger, consolidation, tender or exchange offer, reorganization, recapitalization,
liquidation, purchase, sale or transfer of all or substantially all of the Company’s or its Subsidiaries’ assets or securities,
or other business combination transaction or acquisition proposal (other than the Business Combination Agreement and the Transactions);
and

 

(f)          
against any proposal, action or agreement that would (A) impede, interfere with, delay, postpone, discourage, frustrate, adversely
affect, prevent or nullify any provision of this Agreement, the Business Combination Agreement, the Merger or the other Transactions (including
the economic benefits to ACAH and Merger Sub of the Merger and the other Transactions), (B) result in a breach in any respect of any covenant,
representation, warranty or any other obligation or agreement of the Company under the Business Combination Agreement, (C) result in any
of the conditions set forth in Article 6 of the Business Combination Agreement not being fulfilled, (D) result in a breach of (i) any
covenant, representation or warranty or other obligation or agreement of such Company Stockholder contained in this Agreement, or (ii)
the Company contained in the Business Combination Agreement, or (E) that is otherwise inconsistent with this Agreement, the Business Combination
Agreement or the Transactions.

 

Any such vote shall be cast,
or consent shall be given, for purposes of this Section 2.3, in accordance with such procedures relating thereto as shall ensure
that it is duly counted for purposes of determining that a quorum is present and for purposes of recording in accordance herewith the
results of such vote or consent. Each Company Stockholder hereby agrees that it shall not commit or agree to take any action inconsistent
with the foregoing

 

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Section 2.4           
No Challenges. Each Company Stockholder agrees (and shall cause each of its Affiliates
to agree) not to bring, commence, institute, join in, maintain, voluntarily aid, finance, facilitate, assist, encourage or prosecute,
and agrees to take all actions necessary to opt out of any class in any class action with respect to, any claim, appeal, litigation, arbitration,
derivative, proceeding or otherwise, against ACAH, Merger Sub, the Company or any of their respective successors or directors (a) challenging
the validity of, or seeking to enjoin the operation of, any provision of this Agreement, or (b) alleging a breach of any fiduciary duty
of any Person (including the Board of Directors of the Company or any member or committee thereof) in connection with the evaluation,
negotiation or entry into the Business Combination Agreement or the Transactions contemplated thereby.

 

Section 2.5           
Closing Date Deliverables. Each Company Stockholder shall deliver, or cause to be delivered, substantially simultaneously
with the Effective Time, (a) a duly-executed copy of that certain Amended and Restated Registration Rights Agreement, by and among ACAH,
the Company and the other parties thereto, in substantially the form attached as Exhibit A to the Business Combination Agreement,
(b) a duly-executed copy of that certain Restrictive Covenant Agreement, in favor of ACAH and the Company, in substantially the form attached
as Exhibit B to the Business Combination Agreement, and (c) a duly-executed copy of that certain Lock-up Agreement, in favor of
ACAH, in substantially the form attached as Exhibit B to the Business Combination Agreement.

 

Section 2.6           
Further Assurances. From time to time, and without further consideration, each Company Stockholder shall execute and deliver,
or cause to be delivered, such additional documents, and take, or cause to be taken, all such further actions and do, or cause to be done,
all things reasonably necessary (including under applicable Laws), or reasonably requested by ACAH or the Company, to effect the actions
and consummate the Merger and the other transactions contemplated by this Agreement and the Business Combination Agreement, in each case,
on the terms and subject to the conditions set forth therein and herein, as applicable.

 

Section 2.7           
No Inconsistent Agreement. Each Company Stockholder hereby represents and covenants that, other than this Agreement, such
Company Stockholder has not entered into, and shall not enter into at any time during the Term, (a) any voting arrangement, whether by
proxy, consent, power of attorney, voting agreement, voting trust or otherwise, with respect to the Subject Securities with respect to
any matters set forth in Section 2.3, (b) any grant of a proxy, consent or power of attorney with respect to the Subject Securities,
or (c) any agreement that would restrict, limit, prevent, disable or interfere with the performance of such Company Stockholder’s
obligations hereunder.

 

Section 2.8           
Consent to Disclosure. Each Company Stockholder hereby consents to and authorizes the publication and disclosure in the
Registration Statement / Proxy Statement and in any press release or disclosure document required in connection with the Merger and the
Transactions (including, as and to the extent otherwise required by applicable securities Laws or the SEC or any other securities authorities,
any other documents or communications provided by ACAH or the Company to any Governmental Entity or to securityholders of ACAH) of such
Company Stockholder’s identity and beneficial ownership of Subject Securities and the nature of such Company Stockholder’s
commitments, arrangements and understandings under and relating to this Agreement and, if deemed appropriate by ACAH or the Company, a
copy of this Agreement. Each Company Stockholder shall promptly provide any information reasonably requested by ACAH or the Company for
any regulatory application or filing made or approval sought in connection with the Transactions (including filings with the SEC), and
shall promptly notify ACAH and the Company, as applicable, of any required corrections with respect to any written information supplied
by such Company Stockholder specifically for use in any such regulatory application, filing or disclosure document, if and to the extent
such Company Stockholder becomes aware that any have become false or misleading in any material respect.

 

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Section 2.9           
Termination of Company Stockholders Agreements, Related Agreements. Each Company Stockholder, by this Agreement with respect
to its Subject Securities, severally and not jointly, hereby agrees to take, or cause to be taken, all actions necessary or advisable
to terminate, subject to the Closing and effective as of the Effective Time, (a) all Company Stockholders Agreements, if applicable to
such Company Stockholder, (b) all Company Related Party Transactions, if applicable to such Company Stockholder, and (c) any rights under
any letter or agreement providing for redemption rights, put rights, purchase rights, preemptive rights, rights of first refusal, drag-along
rights, anti-dilution protections or other similar rights not generally available to stockholders of the Company (clauses (a), (b) and
(c), collectively, the “Terminating Rights”) between such Company Stockholder and the Company, in each case, without
any further obligations or Liabilities to the Company or any of its Affiliates (including, from and after the Effective Time, ACAH and
its Affiliates); provided, that the Terminating Rights shall exclude, (i) for the avoidance of doubt, any rights such Company Stockholder
may have that relate to any commercial agreements or arrangements (to the extent such agreements or arrangements do not constitute Company
Related Party Transactions) or employment agreements or arrangements between such Company Stockholder and the Company or any Subsidiary
thereof, which shall survive the Closing in accordance with their terms, and (ii) any indemnification, advancement of expenses and exculpation
rights of any Company Stockholder or any of its Affiliates set forth in the foregoing documents, which shall survive the Closing in accordance
with their terms; provided, further, that all Terminating Rights between the Company and any other holder of Company Convertible
Securities shall also terminate at such time.

 

Section 2.10    
Waiver of Appraisal Rights. Each Company Stockholder hereby unconditionally waives, and agrees not to exercise, assert or
perfect, any rights of appraisal or any dissenters’ rights that such Company Stockholder may have (whether under applicable Law
or otherwise) or could potentially have or acquire in connection with the Merger.

 

ARTICLE
III

REPRESENTATIONS AND WARRANTIES

 

Section 3.1        
Representations and Warranties of the Company Stockholders. Each Company Stockholder represents and warrants as of the date
hereof to ACAH and the Company (solely with respect to itself, himself or herself and not with respect to any other Company Stockholder)
as follows:

 

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(a)         
Organization; Due Authorization. If such Company Stockholder is not an individual, it is duly organized, validly existing
and in good standing under the Laws of the jurisdiction in which it is incorporated, formed, organized or constituted, and the execution,
delivery and performance of this Agreement and the consummation of the transactions contemplated hereby are within such Company Stockholder’s
corporate, limited liability company or organizational powers, have been duly authorized by all necessary corporate, limited liability
company or organizational actions on the part of such Company Stockholder and no other corporate, limited liability company or organizational
actions on the part of such Company Stockholder are necessary to approve this Agreement or to consummate the transactions contemplated
hereby. If such Company Stockholder is an individual, such Company Stockholder has full legal capacity, right and authority to execute
and deliver this Agreement and to perform his or her obligations hereunder. This Agreement has been duly executed and delivered by such
Company Stockholder and, assuming due authorization, execution and delivery by the other parties to this Agreement, this Agreement constitutes
a legally valid and binding obligation of such Company Stockholder, enforceable against such Company Stockholder in accordance with the
terms hereof (except as enforceability may be limited by bankruptcy Laws, other similar Laws affecting creditors’ rights and general
principles of equity affecting the availability of specific performance and other equitable remedies). If this Agreement is being executed
in a representative or fiduciary capacity, the Person signing this Agreement has full power and authority to enter into this Agreement
on behalf of the applicable Company Stockholder.

 

(b)              
Ownership. Such Company Stockholder is the sole record and Beneficial Owner of, has dispositive power over, good title to,
and, in the case of the Subject Shares has voting power (including, without limitation, by proxy or power of attorney) over, all of such
Company Stockholder’s Subject Securities indicated opposite such Company Stockholder’s name on Schedule I attached
hereto, and there exist no Liens or any other limitation or restriction (including any restriction on the right to vote, sell or otherwise
dispose of such Subject Securities (other than transfer restrictions under the Securities Act)) affecting any such Subject Securities,
other than Liens pursuant to (i) this Agreement, (ii) the Company’s Governing Documents, (iii) the Business Combination Agreement,
(iv) the Company Stockholders Agreements or (v) any applicable securities Laws. Such Company Stockholder’s Subject Securities are
the only equity securities in the Company owned of record or Beneficially Owned by such Company Stockholder on the date of this Agreement,
and none of such Company Stockholder’s Subject Securities are subject to any proxy, voting trust or other agreement or arrangement
restricting or otherwise relating to the voting or Transfer of such Subject Securities, except as provided hereunder and under the Company
Stockholders Agreements. Other than the Existing Subject Securities and Company Options set forth opposite such Company Stockholder’s
name on Schedule I, such Company Stockholder does not hold or own any rights to acquire (directly or indirectly) any equity securities
of the Company or any equity securities convertible into, which can be exchanged for, or which will affect the Beneficial Ownership of
the Company Stockholder’s interest in, equity securities of the Company. Such Company Stockholder has not appointed or granted any
proxy or power of attorney that is still in effect with respect to any Subject Securities.

 

(c)              
No Conflicts. The execution and delivery of this Agreement by such Company Stockholder does not, and the performance by
such Company Stockholder of his, her or its obligations hereunder will not, (i) if such Company Stockholder is not an individual, conflict
with or result in a violation of the Governing Documents of such Company Stockholder, (ii) conflict with or violate any Law applicable
to such Company Stockholder or by which any of such Company Stockholder’s assets or properties is bound, (iii) breach, violate,
result in the loss of any benefit under, constitute a default under (or an event which with notice or lapse of time or both would become
a default), result in the termination of or a right of termination, vesting, cancellation, amendment, notification, purchase or sale under,
or result in the creation, acceleration or change of any rights or obligations of any party or the creation of any Lien upon any of the
Subject Securities under, any Contract that is binding on the Company Stockholder or any of his assets or properties, or (iv) require
any consent, approval, authorization, or permit that has not been given or other action that has not been taken by any Person (including
under any Contract binding upon such Company Stockholder or such Company Stockholder’s Subject Securities) to the extent such consent,
approval, authorization, permit or other action would prevent, enjoin or materially delay the performance by such Company Stockholder
of its, his or her obligations under this Agreement.

 

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(d)              
Litigation. There are no Proceedings or Orders pending against, or to the knowledge of such Company Stockholder threatened
against or affecting, such Company Stockholder, which (i) in any manner challenges or seeks to prevent, enjoin or materially delay the
performance by such Company Stockholder of its, his or her obligations under this Agreement , or (ii) could reasonably be expected to
impair or adversely affect the ability of such Company Stockholder to perform its, his or her obligations under this Agreement.

 

(e)              
Adequate Information. Such Company Stockholder is a sophisticated stockholder and has adequate information concerning the
business and financial condition of ACAH and the Company to make an informed decision regarding this Agreement and the Transactions and
has independently and without reliance upon ACAH or the Company and based on such information as such Company Stockholder has deemed appropriate,
made its own analysis and decision to enter into this Agreement. Such Company Stockholder acknowledges that ACAH and the Company have
not made and do not make any representation or warranty, whether express or implied, of any kind or character except as expressly set
forth in this Agreement. Such Company Stockholder acknowledges that the agreements contained herein with respect to the Subject Securities
held by such Company Stockholder are irrevocable.

 

(f)               
Brokerage Fees. No broker, finder, investment banker or other Person is entitled to any brokerage fee, finders’ fee
or other commission in connection with the transactions contemplated by the Business Combination Agreement based upon arrangements made
by such Company Stockholder in his, her or its capacity as a stockholder or, to the knowledge of such Company Stockholder, on behalf of
such Company Stockholder in his, her or its capacity as a stockholder, for which the Company or any of its Affiliates may become liable.

 

(g)              
Acknowledgment. Such Company Stockholder understands and acknowledges that each of ACAH and the Company is entering into
the Business Combination Agreement in reliance upon such Company Stockholder’s execution and delivery of this Agreement and the
representations and warranties, covenants and other agreements of the Company Stockholder contained herein.

 

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ARTICLE
IV

MISCELLANEOUS

 

Section 4.1           
Termination. This Agreement and all of its provisions shall terminate and be of no further force or effect upon the earliest
to occur of (a) the Effective Time, (b) such date and time as the Business Combination Agreement shall be terminated in accordance with
Section 7.1 thereof (the earlier of (a) and (b), the “Expiration Time”) and (c) as to each Company Stockholder, upon
the written agreement of ACAH, the Company and such Company Stockholder. Upon such termination of this Agreement, all obligations of the
parties under this Agreement will terminate, without any liability or other obligation on the part of any party hereto to any Person in
respect hereof or the transactions contemplated hereby, and no party hereto shall have any claim against another (and no Person shall
have any rights against such party), whether under contract, tort or otherwise, with respect to the subject matter hereof; provided,
however, that the termination of this Agreement shall not relieve any party hereto from liability arising in respect of any breach
of this Agreement prior to such termination. This ARTICLE IV shall survive the termination of this Agreement.

 

Section 4.2           
Expenses. All fees and expenses incurred in connection with this Agreement and the transactions contemplated hereby shall
be allocated in accordance with Section 8.6 of the Business Combination Agreement.

 

Section 4.3           
Governing Law. This Agreement shall be governed by and construed in accordance with the laws of the State of Delaware, without
giving effect to any choice of law or conflict of law provision or rule (whether of the State of Delaware or any other jurisdiction) that
would cause the application of the law of any jurisdiction other than the State of Delaware.

 

Section 4.4           
WAIVER OF JURY TRIAL. EACH PARTY HEREBY WAIVES, TO THE FULLEST EXTENT PERMITTED BY LAW, ANY RIGHT TO TRIAL BY JURY OF ANY
PROCEEDING, CLAIM, DEMAND, ACTION, OR CAUSE OF ACTION (I) ARISING UNDER THIS AGREEMENT OR (II) IN ANY WAY CONNECTED WITH OR RELATED OR
INCIDENTAL TO THE DEALINGS OF THE PARTIES IN RESPECT OF THIS AGREEMENT OR ANY OF THE TRANSACTIONS RELATED HERETO, IN EACH CASE, WHETHER
NOW EXISTING OR HEREAFTER ARISING, AND WHETHER IN CONTRACT, TORT, EQUITY, OR OTHERWISE. EACH PARTY HEREBY AGREES AND CONSENTS THAT ANY
SUCH PROCEEDING, CLAIM, DEMAND, ACTION OR CAUSE OF ACTION SHALL BE DECIDED BY COURT TRIAL WITHOUT A JURY AND THAT THE PARTIES MAY FILE
AN ORIGINAL COUNTERPART OF A COPY OF THIS AGREEMENT WITH ANY COURT AS WRITTEN EVIDENCE OF THE CONSENT OF THE PARTIES HERETO TO THE WAIVER
OF THEIR RIGHT TO TRIAL BY JURY. EACH PARTY CERTIFIES AND ACKNOWLEDGES THAT (A) NO REPRESENTATIVE, AGENT OR ATTORNEY OF ANY OTHER PARTY
HAS REPRESENTED, EXPRESSLY OR OTHERWISE, THAT SUCH OTHER PARTY WOULD NOT, IN THE EVENT OF LITIGATION, SEEK TO ENFORCE THE FOREGOING WAIVER,
(B) EACH SUCH PARTY UNDERSTANDS AND HAS CONSIDERED THE IMPLICATIONS OF THIS WAIVER, (C) EACH SUCH PARTY MAKES THIS WAIVER VOLUNTARILY
AND (D) EACH SUCH PARTY HAS BEEN INDUCED TO ENTER INTO THIS AGREEMENT BY, AMONG OTHER THINGS, THE MUTUAL WAIVERS AND CERTIFICATIONS IN
THIS SECTION 4.4.

 

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Section 4.5           
Submission to Jurisdiction. Each of the parties irrevocably and unconditionally submits to the exclusive jurisdiction of
the Chancery Court of the State of Delaware (or, if the Chancery Court of the State of Delaware declines to accept jurisdiction, any state
or federal court within State of New York, New York County), for the purposes of any Proceeding, claim, demand, action or cause of action
(a) arising under this Agreement or (b) in any way connected with or related or incidental to the dealings of the parties in respect of
this Agreement or any of the transactions contemplated hereby, and irrevocably and unconditionally waives any objection to the laying
of venue of any such Proceeding in any such court, and further irrevocably and unconditionally waives and agrees not to plead or claim
in any such court that any such Proceeding has been brought in an inconvenient forum. Each party hereby irrevocably and unconditionally
waives, and agrees not to assert, by way of motion or as a defense, counterclaim or otherwise, in any Proceeding claim, demand, action
or cause of action against such party (i) arising under this Agreement or (ii) in any way connected with or related or incidental to the
dealings of the parties in respect of this Agreement or any of the transactions contemplated hereby, (A) any claim that such party is
not personally subject to the jurisdiction of the courts as described in this Section 4.5 for any reason, (B) that such party or
such party’s property is exempt or immune from the jurisdiction of any such court or from any legal process commenced in such courts
(whether through service of notice, attachment prior to judgment, attachment in aid of execution of judgment, execution of judgment or
otherwise) and (C) that (x) the Proceeding, claim, demand, action or cause of action in any such court is brought against such party in
an inconvenient forum, (y) the venue of such Proceeding, claim, demand, action or cause of action against such party is improper or (z)
this Agreement, or the subject matter hereof, may not be enforced against such party in or by such courts. Each party agrees that service
of any process, summons, notice or document by registered mail to such party’s respective address set forth in Section 4.10
shall be effective service of process for any such Proceeding, claim, demand, action or cause of action.

 

Section 4.6           
Assignment. This Agreement and all of the provisions hereof will be binding upon and inure to the benefit of the parties
hereto and their respective heirs, successors and permitted assigns. Neither this Agreement nor any of the rights, interests or obligations
hereunder will be assigned (including by operation of law) without the prior written consent of the parties hereto. Any attempted assignment
of this Agreement not in accordance with the terms of this Section 4.6 shall be void.

 

Section 4.7           
Remedies. Except as otherwise expressly provided herein, any and all remedies provided herein will be deemed cumulative
with and not exclusive of any other remedy conferred hereby, or by law or equity upon such party, and the exercise by a party of any one
remedy will not preclude the exercise of any other remedy. The parties agree that irreparable damage for which monetary damages, even
if available, would not be an adequate remedy, would occur in the event that the parties do not perform their respective obligations under
the provisions of this Agreement (including failing to take such actions as are required of them hereunder to consummate the transactions
contemplated by this Agreement) in accordance with their specific terms or otherwise breach such provisions. It is accordingly agreed
that the parties shall be entitled to seek an injunction or injunctions, specific performance and other equitable relief to prevent breaches
of this Agreement and to enforce specifically the terms and provisions of this Agreement, in each case, without posting a bond or undertaking
and without proof of damages and this being in addition to any other remedy to which they are entitled at law or in equity. Each of the
parties agrees that it will not oppose the granting of an injunction, specific performance and other equitable relief when expressly available
pursuant to the terms of this Agreement on the basis that the other parties have an adequate remedy at law or an award of specific performance
is not an appropriate remedy for any reason at law or equity.

 

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Section 4.8           
Amendment; Waiver. This Agreement may not be amended, changed, supplemented, waived or otherwise modified or terminated,
except upon the execution and delivery of a written agreement executed by ACAH, the Company and the Company Stockholders.

 

Section 4.9           
Severability. Whenever possible, each provision of this Agreement will be interpreted in such a manner as to be effective
and valid under applicable Law, but if any term or other provision of this Agreement is held to be invalid, illegal or unenforceable under
applicable Law, all other provisions of this Agreement shall remain in full force and effect so long as the economic or legal substance
of the transactions contemplated hereby is not affected in any manner materially adverse to any party. Upon such determination that any
term or other provision of this Agreement is invalid, illegal or unenforceable under applicable Law, the parties shall negotiate in good
faith to modify this Agreement so as to effect the original intent of the parties as closely as possible in an acceptable manner in order
that the transactions contemplated hereby are consummated as originally contemplated to the greatest extent possible.

 

Section 4.10       
Notices. All notices, requests, claims, demands and other communications hereunder shall be in writing and shall be given
(and shall be deemed to have been duly given) by delivery in person, by e-mail (having obtained electronic delivery confirmation thereof
(i.e., an electronic record of the sender that the e-mail was sent to the intended recipient thereof without an “error” or
similar message that such e-mail was not received by such intended recipient)), or by registered or certified mail (postage prepaid, return
receipt requested) (upon receipt thereof) to the other parties as follows:

 

If to ACAH:

 

Atlantic Coastal Acquisition Corp.

6 St Johns Lane, Floor 5

New York, New York 10013

Attention:   Shahraab Ahmad

Email:         shahraab@atlanticcoastalacquisition.com

 

with a copy to (which shall not constitute notice):

 

Pillsbury Winthrop Shaw Pittman LLP

31 West 52nd Street

New York, NY 10019

Attention:  Stephen B Amdur

                        Bianca K. Bowen

Email:         stephen.amdur@pillsburylaw.com

                       bianca.bowen@pillsburylaw.com

 

If to the Company:

 

Essentium, Inc.

19025 N. Heatherwilde Blvd Suite 100

Pflugerville, TX 78660

Attention:   Blake Teipel, Ph.D., Chief Executive
Officer

Email:          blake.teipel@essentium.com

 

    11

     

    

 

with a copy to (which shall not constitute
notice):

 

Latham & Watkins LLP

301 Congress Avenue, Suite 900

Austin, TX 78701

Attention:  Jenifer Smith

                      Nick Dhesi

Email:        jen.smith@lw.com

                      nick.dhesi@lw.com 

 

If to a Company Stockholder:

 

To such Company Stockholder’s address set forth in Schedule
I.

 

or to such other address as the Party to whom notice is given may have
previously furnished to the others in writing in the manner set forth above.

 

Section 4.11       
Counterparts; Electronic Signatures. This Agreement (including any of the closing deliverables contemplated hereby) may
be executed in one or more counterparts, each of which shall be deemed to be an original, but all of which shall constitute one and the
same agreement. Delivery of an executed counterpart of a signature page to this Agreement (including any of the closing deliverables contemplated
hereby) by e-mail, scanned pages or other electronic imaging (including “pdf”, “tif”, “jpg”, DocuSign,
AdobeSign or other similar electronic transmission) shall be effective as delivery of a manually executed counterparty to this Agreement.

 

Section 4.12       
Entire Agreement. This Agreement constitutes the entire agreement among the parties with respect to the subject matter hereof
and supersedes all other prior agreements and understandings, both written and oral, among the parties with respect to the subject matter
hereof; provided, that, for the avoidance of doubt, the foregoing shall not affect the rights and obligations of the parties under
the Business Combination Agreement or any Ancillary Document.

 

[THE REMAINDER OF THIS PAGE IS INTENTIONALLY
BLANK]

 

    12

     

    

 

IN WITNESS WHEREOF, the Company
Stockholders, ACAH, and the Company have each caused this Stockholder Support Agreement to be duly executed as of the date first written
above.

 

		COMPANY STOCKHOLDERS:
	 	 
	 	G. & A. Birdwell Family
                      Limited Partnership
	 	 	 
	 	By:	/s/ Gene R. Birdwell
	 	 	Name: Gene R. Birdwell
	 	 	Title: President

 

		BASF Venture Capital GmbH
	 	 	 
	 	By:	/s/ Markus Solibieda
	 	 	Name: Markus Solibieda
	 	 	Title: Managing Director

 

		Robert Vanman
	 	 	 
	 	By:	/s/ Robert Vanman

 

		Vanman Charitable Trust
	 	 	 
	 	By:	/s/ Robert Vanman
	 	 	Name: Robert Vanman

 

[Signature Page to Stockholder Support Agreement]

 

    13

     

    

 

		Erik Gjovik
	 	 	 
	 	By:	/s/ Erik Gjovik

 

	 	William
Jack MacNeish III
	 	 	 
	 	By:	/s/ William Jack Macneish III

 

	 	Lars Uffhausen
	 	 	 
	 	By:	/s/ Lars Uffhausen

 

	 	Blake Ryland Teipel
	 	 	 
	 	By:	/s/ Blake Ryland Teipel

 

	 	Elisa Marina Teipel
	 	 	 
	 	By:	/s/ Elisa Marina Teipel

 

	 	Ryan Joseph Vano
	 	 	 
	 	By:	/s/ Ryan Joseph Vano

 

	 	Charles Brandon Sweeney
	 	 	 
	 	By:	/s/ Charles Brandon Sweeney

 

[Signature Page to Stockholder Support Agreement]

 

     

     

    

 

		ACAH:
	 	 	 
	 	atlantic Coastal Acquisition Corp.
	 	 	 
	 	By:	/s/ Shahraab Ahmad
	 	 	Name: Shahraab Ahmad
	 	 	Title: Chief Executive Officer

 

[Signature Page to Stockholder Support Agreement]

 

     

     

    

 

		COMPANY:
	 	 	 
	 	Essentium, Inc.
	 	 	 
	 	By:	/s/ Blake Teipel
	 	 	Name: Blake Teipel
	 	 	Title: Chief Executive Officer

 

[Signature Page to Stockholder Support Agreement]

 

     

     

    

 

Schedule I

Beneficial Ownership of Company Stockholders

 

	Company
    Stockholder	 	Shares
    of Common Stock	 	 	Shares
    of Series A Preferred Stock	 	 	Shares
    of Series A-1 Preferred Stock	 	 	Shares
    of Series A-2 Preferred Stock	 	 	Shares
    of Series A-3 Preferred Stock	 	 	Shares
    of Series B Preferred Stock	 	 	Shares
    of Series B-1 Preferred Stock	 	 	Company
    Options	 	 	Convertible
    Notes1	 	 	Notice
    Information
	G. &
    A. Birdwell Family Limited Partnership	 	 	100	 	 	 	 	 	 	 	2,420,002	 	 	 	 	 	 	 	1,072,961	 	 	 	 	 	 	 	779,746	 	 	 	 	 	 	 	1,473,151	 	 	13111
    Paradise Valley Drive 
Houston, TX 77069 

	BASF Venture Capital
    GmbH	 	 	3,787,347	 	 	 	1,890,200	 	 	 	 	 	 	 	 	 	 	 	295,824	 	 	 	279,331	 	 	 	 	 	 	 	 	 	 	 	469,814	 	 	BE01, Benckiserplatz 1 
 67059 Ludwigshafen am

                                                                                 Rhein 
Germany 

	Robert Vanman	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	3,054,127	 	 	 	 	 	 	 	 	 	 	 	399,934	 	 	1844
    San Jacinto Drive 
Allen, TX 75013 

	Vanman Charitable Trust	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	1,396,655	 	 	 	 	 	 	 	 	 	 	 	422,052	 	 	1844
    San Jacinto Drive 
Allen, TX 75013 

	Erik Gjovik	 	 	548,437	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	159,000	 	 	 	 	 	 	c/o
    Essentium, Inc. 
19025 N. Heatherwilde Blvd 
Suite 100 
Pflugerville, TX 78660 

	William Jack MacNeish III	 	 	548,437	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	159,000	 	 	 	 	 	 	c/o
    Essentium, Inc. 
19025 N. Heatherwilde Blvd 
Suite 100 
Pflugerville, TX 78660 

	Lars Uffhausen	 	 	548,437	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	164,000	 	 	 	 	 	 	c/o
    Essentium, Inc. 
19025 N. Heatherwilde Blvd 
Suite 100 
 Pflugerville, TX 78660 

	Blake Ryland Teipel	 	 	543,280	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	174,157	 	 	 	 	 	 	c/o
    Essentium, Inc. 
19025 N. Heatherwilde Blvd 
Suite 100 
 Pflugerville, TX 78660 

	Elisa Marina Teipel	 	 	543,280	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	164,157	 	 	 	 	 	 	c/o
    Essentium, Inc. 
19025 N. Heatherwilde Blvd 
Suite 100 
Pflugerville, TX 78660 

	Ryan Joseph Vano	 	 	543,280	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	159,157	 	 	 	 	 	 	c/o
    Essentium, Inc. 
19025 N. Heatherwilde Blvd 
Suite 100 
Pflugerville, TX 78660 

	Charles Brandon Sweeney	 	 	271,872	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	72,000	 	 	 	 	 	 	c/o
    Essentium, Inc. 
19025 N. Heatherwilde Blvd 
Suite 100 
Pflugerville, TX 78660 

	Total:	 	 	7,334,470	 	 	 	1,890,200	 	 	 	2,420,002	 	 	 	-	 	 	 	1,368,785	 	 	 	4,730,113	 	 	 	779,746	 	 	 	1,051,471	 	 	 	2,764,951	 	 	 

 

 

 

1
This column displays the number of shares of Series B Preferred Stock that the respective Company Stockholder will receive upon a full
conversion at $9 per share of the Company Convertible Notes held by such Company Stockholder.

 

[Schedule I to Stockholder Support Agreement]Exhibit 10.2

 

November 30, 2021

 

Atlantic Coastal Acquisition Corp.

6 St Johns Lane, Floor 5

New York, New York 10013

 

Essentium,
Inc.

19025 N Heatherwilde Blvd, Suite 100

Pflugerville, TX 78660

 

BTIG,
LLC

65 E 55th Street

New York, New York 10022

 

Re: Sponsor Letter Agreement

 

Ladies and Gentlemen:

 

This letter (this “Letter
Agreement”) is being delivered to you in accordance with that certain Business Combination Agreement (the “Business
Combination Agreement”), dated as of November 30, 2021, by and among Atlantic Coastal Acquisition Corp., a Delaware corporation
(the “ACAH”), Essentium, Inc., a Delaware corporation (the “Company”), and Alpha Merger
Sub 1, Inc., a Delaware corporation and wholly-owned subsidiary of ACAH (“Merger Sub”) and hereby amends an
restates in its entirety that certain letter (the “Prior Letter Agreement”), dated as of March 3, 2021, by and
among Atlantic Coastal Acquisition Management, LLC (the “Sponsor”) and each of Shahraab Ahmad, Burt Jordan,
Anthony D. Eisenberg, Ronald C. Warrington, Ned Sizer, Joanna Lord, Bryan Dove, Iqbaljit Kahlon, and Daniel M. Tapiero, who are members
of the board of directors and/or management team of ACAH (collectively, the “Insiders”). Capitalized terms used
herein are defined in paragraph 15. Capitalized terms used herein but not defined shall have their respective meanings set forth in the
Business Combination Agreement.

 

In order to induce the Company
and ACAH to enter into the Business Combination Agreement and for other good and valuable consideration, the receipt and sufficiency of
which are hereby acknowledged, each of the Sponsor, the Insiders, and Atlantic Coastal Finance Company LLC, a Delaware limited liability
company (“ACF” and collectively, the “ACAH Insiders”), hereby agrees with ACAH, BTIG,
LLC (“BTIG”) and, at all times prior to any termination of the Business Combination Agreement, the Company as
follows:

 

		1.	From the date hereof until the earlier of the Effective Time or such date and time as the Business Combination
Agreement shall be terminated in accordance with its terms (the “Term”) each ACAH Insider hereby unconditionally
and irrevocably agrees that (a) at any meeting of the stockholders of ACAH (including any adjournment or postponement thereof), however
called, (b) in any action by written consent of the stockholders of ACAH requested by the board of directors of ACAH or otherwise undertaken
in connection with the transactions contemplated by the Business Combination Agreement (the “Transactions”)
(which written consent shall be delivered promptly), and (c) in any other circumstance upon which a vote, consent or other approval of
the stockholders of ACAH is sought, such ACAH Insider shall, if a meeting is held, appear at the meeting, in person or by proxy, or otherwise
cause its Subject Shares to be counted as present thereat for purposes of establishing a quorum, and such ACAH Insider shall vote or provide
consent or approval (or cause to be voted or consented or approved), in person or by proxy, all of its Subject Shares:

 

     

     

    

 

(a)
to approve and adopt the Business Combination Agreement and the Transactions;

 

(b)
in any other circumstances upon which a consent or other approval is required under the Governing Documents of ACAH or otherwise
sought with respect to the Business Combination Agreement or the Transactions, to vote, consent or approve (or cause to be voted, consented
or approved) all of such ACAH Insiders’ Subject Shares held at such time in favor thereof;

 

(c)
to approve and adopt any proposal to adjourn or postpone such meeting of the stockholders of ACAH to a later date if there are
not sufficient votes to adopt the Business Combination Agreement and/or if there are not sufficient shares present in person or by proxy
at such meeting of the stockholders of ACAH to constitute a quorum; provided that, in no event shall the ACAH Insiders be required
to adjourn a meeting of the stockholders of ACAH to a date that is beyond the Termination Date;

 

(d)
against and withhold consent with respect to any merger, consolidation, tender or exchange offer, reorganization, recapitalization,
liquidation, purchase, sale or transfer of all or substantially all of ACAH’s or its Subsidiaries’ assets or securities, or
other business combination transaction or acquisition proposal (other than the Business Combination Agreement and the Transactions); and

 

(e)
against any proposal, action or agreement that would (A) impede, interfere with, delay, postpone, discourage, frustrate, adversely
affect, prevent or nullify any provision of this Letter Agreement, the Business Combination Agreement, or the Transactions (including
the economic benefits to the Company, ACAH and Merger Sub of the Transactions), (B) result in a breach in any respect of any covenant,
representation, warranty or any other obligation or agreement of ACAH under the Business Combination Agreement, (C) result in any of the
conditions set forth in Article 6 of the Business Combination Agreement not being fulfilled, (D) result in a breach of (i) any covenant,
representation or warranty or other obligation or agreement of such ACAH Insider contained in this Agreement, or (ii) ACAH contained in
the Business Combination Agreement, or (E) that is otherwise inconsistent with this Agreement, the Business Combination Agreement or the
Transactions.

 

Any
vote cast pursuant to this paragraph 1 shall be cast, or consent shall be given, in accordance with such procedures relating thereto
as shall ensure that it is duly counted for purposes of determining that a quorum is present and for purposes of recording in accordance
herewith the results of such vote or consent. Each ACAH Insider hereby agrees that it shall not commit or agree to take any action inconsistent
with the foregoing.

 

		2.	Each ACAH Insider agrees (and shall cause each of its Affiliates to agree) not to bring, commence, institute,
join in, maintain, voluntarily aid, finance, facilitate, assist, encourage or prosecute, and agrees to take all actions necessary to opt
out of any class in any class action with respect to, any claim, appeal, litigation, arbitration, derivative, proceeding or otherwise,
against ACAH, Merger Sub, the Company or any of their respective successors or directors (a) challenging the validity of, or seeking to
enjoin the operation of, any provision of this Letter Agreement, or (b) alleging a breach of any fiduciary duty of any Person (including
the board of directors of ACAH or any member or committee thereof) in connection with the evaluation, negotiation or entry into the Business
Combination Agreement or the Transactions.

 

    2

     

    

 

		3.	During the Term and except as otherwise contemplated under that certain Loan and Security Agreement, dated
as of the date hereof, by and between ACF and Cantor Fitzgerald Securities (the “Loan Agreement”), each ACAH
Insider agrees not, and shall cause each of its Affiliates not to, (a) Transfer any of the Subject Shares or any other interest specifically
therein (including by tendering into any tender or exchange offer by any Person other than ACAH or any of its Subsidiaries), (b) publicly
announce any intention to effect any Transfer prior to Closing, (c) enter into any agreement, arrangement or understanding, directly or
indirectly, with any Person, or take any other action that would prevent or disable such ACAH Insider from performing his, her or its
obligations under this Agreement, (d) deposit any of the Subject Shares into a voting trust, enter into any agreement, arrangement or
understanding with any Person to vote or give instructions inconsistent with this Letter Agreement with respect to the Subject Shares,
or grant any proxy or power of attorney with respect thereto, or (e) commit or agree, directly or indirectly, to take any of the foregoing
actions. Any Transfer in violation of this paragraph 3 with respect to an ACAH Insider’s Subject Shares shall be null and void ab
initio.

 

		4.	In the event that, during the Term, (a) any Subject Shares are issued to an ACAH Insider after the date
of this Letter Agreement pursuant to any stock dividend or distribution, stock split, recapitalization, reclassification, combination
or exchange of Subject Shares or otherwise, (b) an ACAH Insider purchases or otherwise acquires Beneficial Ownership of any Subject Shares
or (c) an ACAH Insider acquires the right to vote or share in the voting of any Subject Shares (clauses (a), (b) and (c), collectively,
the “New Securities”), then such New Securities acquired or purchased by such ACAH Insider shall be subject
to the terms of this Letter Agreement to the same extent as if they constituted the Subject Shares owned by such ACAH Insider as of the
date hereof. Other than Transfers pursuant to the Loan Agreement, each ACAH Insider hereby agrees to notify ACAH and the Company in writing
as promptly as practicable of any acquisition of New Securities.

 

		5.	From time to time, and without further consideration, each ACAH Insider shall execute and deliver, or
cause to be delivered, such additional documents, and take, or cause to be taken, all such further actions and do, or cause to be done,
all things reasonably necessary (including under applicable Laws), or reasonably requested by ACAH or the Company, to effect the actions
and consummate the Merger and the other transactions contemplated by this Agreement and the Business Combination Agreement, in each case,
on the terms and subject to the conditions set forth therein and herein, as applicable.

 

		6.	Each ACAH Insider hereby represents and covenants that, other
than this Letter Agreement, such ACAH Insider has not entered into, and shall not enter into at any time during the Term, (a) any voting
arrangement, whether by proxy, consent, power of attorney, voting agreement, voting trust or otherwise, with respect to the Subject Shares,
(b) any grant of a proxy, consent or power of attorney with respect to the Subject Shares, or (c) any agreement that would restrict,
limit, prevent, disable or interfere with the performance of such ACAH Insider’s obligations hereunder.

 

    3

     

    

 

		7.	Each ACAH Insider hereby consents to and authorizes the publication
and disclosure in the Registration Statement / Proxy Statement and in any press release or disclosure document required in connection
with the Merger and the Transactions (including, as and to the extent otherwise required by applicable securities Laws or the SEC or
any other securities authorities, any other documents or communications provided by ACAH or the Company to any Governmental Entity or
to securityholders of ACAH) of such ACAH Insider’s identity and beneficial ownership of Subject Shares and the nature of such ACAH
Insider’s commitments, arrangements and understandings under and relating to this Letter Agreement and, if deemed appropriate by
ACAH or the Company, a copy of this Letter Agreement. Each ACAH Insider shall promptly provide any information reasonably requested by
ACAH or the Company for any regulatory application or filing made or approval sought in connection with the Transactions (including filings
with the SEC), and shall promptly notify ACAH and the Company, as applicable, of any required corrections with respect to any written
information supplied by such ACAH Insider specifically for use in any such regulatory application, filing or disclosure document, if
and to the extent such ACAH Insider becomes aware that any have become false or misleading in any material respect.

 

		8.	Each ACAH Insider hereby unconditionally waives, and agrees
not to exercise, assert or perfect, any rights of appraisal or any dissenters’ rights that such ACAH Insider may have (whether
under applicable Law or otherwise) or could potentially have or acquire in connection with the Merger.

 

		9.	Subject to, and in connection with, the consummation of the
Transactions, the ACAH Insiders each agree to enter into a lock-up agreement, a form of which is attached as Exhibit A hereto
(each, a “Lock-Up Agreement”), and a registration rights agreement, a form of which is attached to the Business
Combination Agreement as an exhibit thereto.

 

		10.	Each ACAH Insider represents and warrants as of the date hereof
to ACAH and the Company (solely with respect to itself, himself or herself and not with respect to any other ACAH Insider) as follows:

 

(a)
If such ACAH Insider is not an individual, it is duly organized, validly existing and in good standing under the Laws of the jurisdiction
in which it is incorporated, formed, organized or constituted, and the execution, delivery and performance of this Letter Agreement and
the consummation of the transactions contemplated hereby are within such ACAH Insider’s corporate, limited liability company or
organizational powers, have been duly authorized by all necessary corporate, limited liability company or organizational actions on the
part of such ACAH Insider and no other corporate, limited liability company or organizational actions on the part of such ACAH Insider
are necessary to approve this Agreement or to consummate the transactions contemplated hereby. If such ACAH Insider is an individual,
such ACAH Insider has full legal capacity, right and authority to execute and deliver this Agreement and to perform his or her obligations
hereunder. This Letter Agreement has been duly executed and delivered by such ACAH Insider and, assuming due authorization, execution
and delivery by the other parties to this Agreement, this Letter Agreement constitutes a legally valid and binding obligation of such
ACAH Insider, enforceable against such ACAH Insider in accordance with the terms hereof (except as enforceability may be limited by bankruptcy
Laws, other similar Laws affecting creditors’ rights and general principles of equity affecting the availability of specific performance
and other equitable remedies). If this Letter Agreement is being executed in a representative or fiduciary capacity, the Person signing
this Agreement has full power and authority to enter into this Agreement on behalf of the applicable ACAH Insider.

 

    4

     

    

 

(b)
Except as otherwise set forth on Schedule I, such ACAH Insider is the sole record and Beneficial Owner of, has dispositive
power over, good title to, and, in the case of the Subject Shares has voting power (including, without limitation, by proxy or power of
attorney) over, all of such ACAH Insider’s Subject Shares indicated opposite such ACAH Insider’s name on Schedule I
attached hereto, and there exist no Liens or any other limitation or restriction (including any restriction on the right to vote, sell
or otherwise dispose of such Subject Shares (other than transfer restrictions under the Securities Act)) affecting any such Subject Shares,
other than Liens pursuant to (i) this Letter Agreement, (ii) ACAH’s Governing Documents, (iii) the Business Combination Agreement
and any other agreements contemplated thereunder, (iv) the Loan Agreement, or (v) any applicable securities Laws. Except as set forth
in the Loan Agreement, such ACAH Insider’s Subject Shares are the only equity securities in ACAH owned of record or Beneficially
Owned by such ACAH Insider on the date of this Letter Agreement, and none of such ACAH Insider’s Subject Shares are subject to any
proxy, voting trust or other agreement or arrangement restricting or otherwise relating to the voting or Transfer of such Subject Shares.
Except as listed on Schedule I and the Loan Agreement, such ACAH Insider does not hold or own any rights to acquire (directly or
indirectly) any equity securities of ACAH or any equity securities convertible into, which can be exchanged for, or which will affect
the Beneficial Ownership of the ACAH Insider’s interest in, equity securities of ACAH. Such ACAH Insider has not appointed or granted
any proxy or power of attorney that is still in effect with respect to any Subject Shares.

 

(c)
The execution and delivery of this Letter Agreement by such ACAH Insider does not, and the performance by such ACAH Insider of
his, her or its obligations hereunder will not, (i) if such ACAH Insider is not an individual, conflict with or result in a violation
of the Governing Documents of such ACAH Insider, (ii) conflict with or violate any Law applicable to such ACAH Insider or by which any
of such ACAH Insider’s assets or properties is bound, (iii) breach, violate, result in the loss of any benefit under, constitute
a default under (or an event which with notice or lapse of time or both would become a default), result in the termination of or a right
of termination, vesting, cancellation, amendment, notification, purchase or sale under, or result in the creation, acceleration or change
of any rights or obligations of any party or the creation of any Lien upon any of the Subject Shares under, any Contract that is binding
on the ACAH Insider or any of his assets or properties, or (iv) require any consent, approval, authorization, or permit that has not been
given or other action that has not been taken by any Person (including under any Contract binding upon such ACAH Insider or such ACAH
Insider’s Subject Shares) to the extent such consent, approval, authorization, permit or other action would prevent, enjoin or materially
delay the performance by such ACAH Insider of its, his or her obligations under this Agreement.

 

    5

     

    

 

(d)
There are no Proceedings or Orders pending against, or to the knowledge of such ACAH Insider threatened against or affecting, such
ACAH Insider, which (i) in any manner challenges or seeks to prevent, enjoin or materially delay the performance by such ACAH Insider
of its, his or her obligations under this Letter Agreement, or (ii) could reasonably be expected to impair or adversely affect the ability
of such ACAH Insider to perform its, his or her obligations under this Letter Agreement.

 

(e)
Such ACAH Insider is a sophisticated stockholder and has adequate information concerning the business and financial condition of
ACAH and the Company to make an informed decision regarding this Letter Agreement and the Transactions and has independently and without
reliance upon ACAH or the Company and based on such information as such ACAH Insider has deemed appropriate, made its own analysis and
decision to enter into this Agreement. Such ACAH Insider acknowledges that ACAH and the Company have not made and do not make any representation
or warranty, whether express or implied, of any kind or character except as expressly set forth in this Agreement. Such ACAH Insider acknowledges
that the agreements contained herein with respect to the Subject Shares held by such ACAH Insider are irrevocable.

 

(f)
Except as set forth in the Business Combination Agreement, including any schedule thereto, no broker, finder, investment banker
or other Person is entitled to any brokerage fee, finders’ fee or other commission in connection with the transactions contemplated
by the Business Combination Agreement based upon arrangements made by such ACAH Insider in his, her or its capacity as a stockholder or,
to the knowledge of such ACAH Insider, on behalf of such ACAH Insider in his, her or its capacity as a stockholder, for which the ACAH
Insider or any of its Affiliates may become liable.

 

(g)
Such ACAH Insider understands and acknowledges that each of ACAH and the Company is entering into the Business Combination Agreement
in reliance upon such ACAH Insider’s execution and delivery of this Agreement and the representations and warranties, covenants
and other agreements of the ACAH Insider contained herein.

 

		11.	Each ACAH Insider hereby agrees and acknowledges that: (i) ACAH and, prior to termination of the Business
Combination Agreement, the Company would be irreparably injured in the event of a breach by such ACAH Insider of its, his or her obligations
under this paragraph 12 or paragraphs 1, 2 or 13(a) as applicable, of this Letter Agreement, (ii) monetary damages may not be an adequate
remedy for such breach and (iii) the non-breaching party shall be entitled to injunctive relief, in addition to any other remedy that
such party may have in law or in equity, in the event of such breach.

 

		12.	

 

(a)
The Sponsor and each ACAH Insider agrees that it, he or she shall not Transfer any Private Placement Warrants (or shares of Common
Stock issued or issuable upon the exercise of the Private Placement Warrants), until 30 days after the completion of the Transactions
(the “Private Placement Warrants Lock-up Period”).

 

(b)
Notwithstanding the provisions set forth in paragraph 13(a), Transfers of the Private Placement Warrants and shares of Common Stock
issued or issuable upon the exercise or conversion of the Private Placement Warrants and that are held by the Sponsor, any ACAH Insider
or any of their permitted transferees (that have complied with this paragraph 13(b)), are permitted (a) to any persons (including their
affiliates and members) participating in the private placement of the Private Placement Warrants; (b) to the Company’s founders,
or to the Company’s officers, directors and employees; (c) in the case of an entity, as a distribution to its, partners, stockholders
or members upon its liquidation; (d) by bona fide gift to a member of the holder’s immediate family or to a trust, the beneficiary
of which is a member of the holder’s immediate family, for estate planning purposes; (e) by virtue of the laws of descent and distribution
upon death; (f) pursuant to a qualified domestic relations order; (g) by certain pledges to secure obligations incurred in connection
with purchases of the Company’s securities; (h) by private sales or transfers at prices no greater than the price at which the securities
were originally purchased; or (i) to the Company for no value for cancellation in connection with the completion of the Transactions;
provided, that, in the case of clauses (a) through (h), any such transferees enter into a written agreement with the Company agreeing
to be bound by the transfer restrictions in this Letter Agreement.

 

    6

     

    

 

		13.	Each ACAH Insider has full right and power, without violating any agreement to which it is bound (including,
without limitation, any non-competition or non-solicitation agreement with any employer or former employer), to enter into this Letter
Agreement.

 

		14.	As used herein:

 

(a)
“Beneficial Ownership” shall be interpreted in accordance with the term “beneficial owner”
as defined in Rule 13d-3 adopted by the SEC under the Exchange Act; provided that, notwithstanding the generality of the foregoing, for
purposes of determining Beneficial Ownership, a Person shall be deemed to be the Beneficial Owner of any securities which such Person
has the right to acquire pursuant to any agreement, arrangement or understanding or upon the exercise of conversion rights, exchange rights,
warrants or options, or otherwise (irrespective of whether the right to acquire such securities is exercisable immediately or only after
the passage of time, including the passage of time in excess of sixty (60) days, the satisfaction of any conditions, the occurrence of
any event or any combination of the foregoing). The terms “Beneficial Ownership,” “Beneficially Own” and “Beneficially
Owned” shall have a correlative meaning.

 

(b)
“Common Stock” means the Company’s Class A common stock, par value $0.0001 per share.

 

(c)
“Founder Shares” means the 8,625,000 shares of the Company’s Class B common stock, par value $0.0001
per share, initially issued to the Sponsor.

 

(d)
“Parties” means the ACAH Insiders, ACAH, BTIG, and the Company.

 

(e)
“Private Placement Warrants” means the warrants to purchase up to 6,066,667 shares of Common Stock that
the Sponsor purchased for an aggregate purchase price of $9,100,000, or $1.50 per warrant, in a private placement that occurred simultaneously
with the consummation of the underwritten initial public offering of the Company’s units.

 

    7

     

    

 

(f)
“Subject Shares” means, with respect to an ACAH Insider, the ACAH Common Shares and ACAH Warrants as
are indicated opposite such ACAH Insider’s name on Schedule I attached hereto, together with any ACAH Common Shares of which
ownership of (i) record and Beneficial Ownership, (ii) the power to vote (including, without limitation, by proxy or power of attorney)
or (iii) any dispositive power, is hereafter acquired by such ACAH Insider during the Term.

 

(g)
“Transfer” means means, directly or indirectly, to (i) sell, offer to sell, contract or otherwise agree
to sell, transfer, convey, exchange, assign, deposit, hypothecate, loan, pledge, encumber (including creating or incurring any Lien upon),
grant any option to purchase or otherwise dispose of or agree to dispose of (including by gift, merger, consolidation by operation of
Law or otherwise (including by conversion into securities or other consideration), either voluntarily or involuntarily, or by tendering
into any tender or exchange offer), file (or participate in the filing of) a registration statement with the SEC (other than the Registration
Statement / Proxy Statement) or establish or increase a put equivalent position or liquidate or decrease a call equivalent position within
the meaning of Section 16 of the Exchange Act, with respect to any Subject Shares (or any security convertible or exchangeable into Subject
Shares), (ii) enter into any swap or other arrangement that transfers to another, in whole or in part, any of the economic consequences
of ownership of any Subject Shares (or any security convertible or exchangeable into Subject Shares), or (iii) enter into any contract,
option or other arrangement or understanding, directly or indirectly, to take any of the foregoing actions.

 

		15.	This Letter Agreement and the other agreements referenced herein constitute the entire agreement and understanding
of the ACAH Insiders in respect of the subject matter hereof and supersedes all prior understandings, agreements, or representations by
or among the ACAH Insiders, written or oral, to the extent they relate in any way to the subject matter hereof or the transactions contemplated
hereby. This Letter Agreement may not be changed, amended, modified or waived (other than to correct a typographical error) as to any
particular provision, except by a written instrument executed by each of the Parties; provided, that the Company’s execution of
such an instrument will not be required after any termination of the Business Combination Agreement.

 

		16.	No ACAH Insider may assign either this Letter Agreement or any of its rights, interests, or obligations
hereunder without the prior written consent of each of the other Parties (except that, following any termination of the Business Combination
Agreement, no consent from the Company shall be required). Any purported assignment in violation of this paragraph 17 shall be void and
ineffectual and shall not operate to transfer or assign any interest or title to the purported assignee. This Letter Agreement shall be
binding on each ACAH Insider and their respective successors, heirs and assigns and permitted transferees.

 

		17.	Nothing in this Letter Agreement shall be construed to confer upon, or give to, any person or corporation
other than the parties hereto any right, remedy or claim under or by reason of this Letter Agreement or of any covenant, condition, stipulation,
promise or agreement hereof. All covenants, conditions, stipulations, promises and agreements contained in this Letter Agreement shall
be for the sole and exclusive benefit of the Parties and their successors, heirs, personal representatives and assigns and permitted transferees.

 

    8

     

    

 

		18.	This Letter Agreement may be executed in one or more counterparts, each of which shall be deemed to be
an original, but all of which shall constitute one and the same agreement. Delivery of an executed counterpart of a signature page to
this Letter Agreement by e-mail, scanned pages or other electronic imaging (including “pdf,” “tif,” “jpg,”
DocuSign, AdobeSign or other similar electronic transmission) shall be effective as delivery of a manually executed counterparty to this
Letter Agreement.

 

		19.	Whenever possible, each provision of this Letter Agreement will be interpreted in such a manner as to
be effective and valid under applicable Law, but if any term or other provision of this Letter Agreement is held to be invalid, illegal
or unenforceable under applicable Law, all other provisions of this Letter Agreement shall remain in full force and effect so long as
the economic or legal substance of the transactions contemplated hereby is not affected in any manner materially adverse to any party.
Upon such determination that any term or other provision of this Letter Agreement is invalid, illegal or unenforceable under applicable
Law, the Parties shall negotiate in good faith to modify this Letter Agreement so as to effect the original intent of the parties as closely
as possible in an acceptable manner in order that the transactions contemplated hereby are consummated as originally contemplated to the
greatest extent possible.

 

		20.	Each of the Parties irrevocably and unconditionally submits to the exclusive jurisdiction of the Chancery
Court of the State of Delaware (or, if the Chancery Court of the State of Delaware declines to accept jurisdiction, any state or federal
court within State of New York, New York County), for the purposes of any Proceeding, claim, demand, action or cause of action (a) arising
under this Letter Agreement or (b) in any way connected with or related or incidental to the dealings of the Parties in respect of
this Letter Agreement or any of the transactions contemplated hereby, and irrevocably and unconditionally waives any objection to the
laying of venue of any such Proceeding in any such court, and further irrevocably and unconditionally waives and agrees not to plead or
claim in any such court that any such Proceeding has been brought in an inconvenient forum. Each Party hereby irrevocably and unconditionally
waives, and agrees not to assert, by way of motion or as a defense, counterclaim or otherwise, in any Proceeding claim, demand, action
or cause of action against such Party (i) arising under this Letter Agreement or (ii) in any way connected with or related or incidental
to the dealings of the Parties in respect of this Letter Agreement or any of the transactions contemplated hereby or any of the transactions
contemplated thereby, (A) any claim that such Party is not personally subject to the jurisdiction of the courts as described in this paragraph
21 for any reason, (B) that such Party or such Party’s property is exempt or immune from the jurisdiction of any such court or from
any legal process commenced in such courts (whether through service of notice, attachment prior to judgment, attachment in aid of execution
of judgment, execution of judgment or otherwise) and (C) that (x) the Proceeding, claim, demand, action or cause of action in any
such court is brought against such Party in an inconvenient forum, (y) the venue of such Proceeding, claim, demand, action or cause
of action against such Party is improper or (z) this Agreement, or the subject matter hereof, may not be enforced against such Party
in or by such courts. Each Party agrees that service of any process, summons, notice or document by registered mail as set forth in paragraph
22 shall be effective service of process for any such Proceeding, claim, demand, action or cause of action

 

    9

     

    

 

		21.	All notices, requests, claims, demands and other communications hereunder shall be in writing and shall
be given (and shall be deemed to have been duly given) by delivery in person, by e-mail (having obtained electronic delivery confirmation
thereof (i.e., an electronic record of the sender that the e-mail was sent to the intended recipient thereof without an “error”
or similar message that such e-mail was not received by such intended recipient)), or by registered or certified mail (postage prepaid,
return receipt requested) (upon receipt thereof) to the other Parties as follows:

 

If to ACAH or any
ACAH Insider, to:

 

Atlantic Coastal Acquisition Corp.

6 St Johns Lane

New York, NY 10013

 

If to BTIG, to:

 

BTIG,
LLC

65 E 55th Street

New York, New York 10022

 

If to the Company:

 

Essentium, Inc.

19025 N Heatherwilde Blvd, Suite 100

Pflugerville, TX 78660

 

		22.	This Letter Agreement shall terminate on the Closing. In the event of any termination of the Business
Combination Agreement prior to the Closing, this Letter Agreement shall be of no force and effect and shall revert to the Prior Letter
Agreement, which the Parties agree shall be in full force and effect upon such termination. No such termination or reversion shall relieve
the Parties from any liability resulting from a breach of this Letter Agreement occurring prior to such termination or reversion.

 

[Signature Page Follows]

 

    10

     

    

 

	 	Sincerely,
	 	 
	 	Atlantic Coastal Acquisition
    Management LLC
	 	 
	 	By:	/s/
    Shahraab Ahmad
	 	 	Name: Shahraab Ahmad
	 	 	Title: Authorized Signatory

 

	 	/s/
    Shahraab Ahmad
	 	Shahraab Ahmad
	 	 
	 	/s/ Burt Jordan
	 	Burt Jordan
	 	 
	 	/s/ Anthony D.
    Eisenberg
	 	Anthony D. Eisenberg
	 	 
	 	/s/ Ronald C.
    Warrington
	 	Ronald C. Warrington
	 	 
	 	/s/ Ned Sizer
	 	Ned Sizer
	 	 
	 	/s/ Joanna Lord
	 	Joanna Lord
	 	 
	 	/s/ Bryan Dove
	 	Bryan Dove
	 	 
	 	/s/ Iqbaljit Kahlon
	 	Iqbaljit Kahlon
	 	 
	 	/s/ Daniel M.
    Tapiero
	 	Daniel M. Tapiero

 

	 	Atlantic Coastal Finance Company
    LLC
	 	 
	 	By:	/s/
    Shahraab Ahmad
	 	 	Name: Shahraab Ahmad
	 	 	Title: Authorized Signatory

 

[Signature Page to Letter Agreement]

 

     

     

    

 

	Acknowledged and Agreed:	 
	 	 
	Atlantic Coastal Acquisition
    Corp.	 
	 	 
	By:	/s/
    Shahraab Ahmad	 
	 	Name: Shahraab Ahmad	 
	 	Title: Chief Executive Officer	 
	 	 
	BTIG, LLC	 
	 	 
	By:	/s/ Gil Ottensoser	 
	 	Name: Gil Ottensoser	 
	 	Title: Managing Director	 
	 	 
	Essentium, Inc.	 
	 	 
	By:	/s/ Blake Teipel	 
	 	Name: Blake Teipel	 
	 	Title: Chief Executive Officer	 

 

[Signature Page to Letter Agreement]

 

     

     

    

 

Schedule
I

Beneficial Ownership

 

	ACAH Insider	 	ACAH Class B

 Shares	 	 	ACAH

 Private

 Placement

 Warrants	 
	Atlantic Coastal Acquisition Management LLC	 	 	8,425,000	 	 	 	6,066,667	 
	Shahraab Ahmad(1)	 	 	8,425,000	 	 	 	6,066,667	 
	Burt Jordan	 	 	-	 	 	 	-	 
	Anthony D. Eisenberg	 	 	-	 	 	 	-	 
	Ronald C. Warrington	 	 	-	 	 	 	-	 
	Ned Sizer	 	 	-	 	 	 	-	 
	Joanna Lord	 	 	50,000	 	 	 	-	 
	Bryan Dove	 	 	50,000	 	 	 	-	 
	Iqbaljit Kahlon	 	 	50,000	 	 	 	-	 
	Daniel M. Tapiero	 	 	50,000	 	 	 	-	 
	Atlantic Coastal Finance Company LLC	 	 	-	 	 	 	-	 
	Total:	 		8,625,000	 	 		6,066,667	 

	 	 	 
		(1)	Represents shares held by Atlantic
Coastal Acquisition Management LLC. Shahraab Ahmad is the manager and the majority owner of Atlantic
Coastal Acquisition Management LLC. Accordingly, Mr. Ahmad may be deemed to beneficially own all of the shares held by Atlantic
Coastal Acquisition Management LLC. Mr. Ahmad disclaims beneficial ownership of any securities held by Atlantic
Coastal Acquisition Management LLC except to the extent of his pecuniary interest therein.

 

     

     

    

 

Exhibit
A

Form of Lock-Up Agreement

 

(attached hereto)

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