EXHIBIT "A"

                                  EXHIBIT 10.1



                               OPTION CERTIFICATE



     THIS IS TO CERTIFY that 3D Systems Corporation, a Delaware corporation (the
"COMPANY"), has granted to the employee of the Company named below a
non-statutory stock option (the "OPTION") to purchase shares of the Company's
Common Stock (the "SHARES"), and upon the terms and conditions determined by the
Compensation Committee (the "COMMITTEE") of the Board of Directors of the
Company (the "BOARD"), as follows:

     NAME OF OPTIONEE:              G. Walter Loewenbaum, III
     ----------------

     ADDRESS OF OPTIONEE:           c/o 3D Systems Corporation
                                    26081 Avenue Hall
                                        Valencia, CA 91355

     NUMBER OF SHARES:              150,000
     ----------------

     OPTION EXERCISE PRICE:         $ 6.6125(1) per Share
     ---------------------

     DATE OF GRANT:                 July 1, 1999
     -------------

     OPTION EXPIRATION DATE:        Ten years from the Date of Grant.
     ----------------------

     EXERCISE SCHEDULE: The Option shall become exercisable in full six months
from the Date of Grant, and the Option may be exercised as to any and all shares
of Common Stock after such six-month period has elapsed and prior to the
expiration or termination of the Option, pursuant to its terms.

     OUTSIDE OF 1996 STOCK INCENTIVE PLAN: The Option has been granted outside
the 1996 Stock Incentive Plan and is not subject to the terms thereof.

     SUMMARY OF OTHER TERMS: This Option is defined in the Stock Option
Agreement (Non-Statutory Stock Option) (the "OPTION AGREEMENT") which is
attached to this Option Certificate (the "CERTIFICATE") as Annex I. This
Certificate summarizes certain of the provisions of the Option Agreement for
your information, but is not complete. Your rights are governed by the Option
Agreement, NOT by this summary. The Company strongly suggests that you carefully
review the full Option Agreement prior to signing this Certificate or exercising
the Option.

     Among the terms of the Option Agreement are the following:

     TERMINATION OF EMPLOYMENT: While the Option terminates on the Option
Expiration Date, it will terminate earlier upon the termination of your
Relationship, as defined in the Option

------------------

(1) Based on the 115% of the closing price of the Common Stock on May 3, 1999.

                                  Exhibit "A"


<PAGE>


Agreement, with the Company or any direct or indirect subsidiary of the Company
(transfer of employment from one subsidiary to another will not constitute
termination of your Relationship). If your Relationship ends due to retirement
or death, the Option terminates eighteen months after the date of retirement or
death, and is exercisable during such eighteen-month period as to the portion of
the Option which had vested prior to the date of retirement or death. If your
Relationship ends due to disability, the Option terminates twelve months after
the date of disability, and is exercisable during such twelve-month period as to
the portion of the Option which had vested prior to the date of disability. If
it is determined that you have committed an act of misconduct described in
Section 5(b) of the Option Agreement, or during the period when your rights
under the Option have been suspended by the Company pursuant to Section 5(b),
the Option will terminate immediately. In all other cases, the Option terminates
ninety days after the date of termination of your Relationship, and is
exercisable during such time period as to the portion of the Option which had
vested prior to the date of termination of your Relationship. See Section 5 of
the attached Option Agreement.

     TRANSFER: The Option is personal to you, and cannot be sold, transferred,
assigned or otherwise disposed of to any other person, except upon your death.
See Section 13(d) of the attached Option Agreement.

     EXERCISE: You can exercise the Option (while it is exercisable), in whole
or in part, by delivering to the Company a Notice of Exercise identical to
Exhibit "A" attached to the Option Agreement, accompanied by payment of, or
provision pursuant to the Option Agreement for the payment of, the Exercise
Price for the Shares to be purchased. The Company may require you to submit
certain written assurances to the Company with respect to your status as a
shareholder. The Company will then issue a certificate to you for the Shares you
have purchased. You are under no obligation to exercise the Option. See Section
4 of the attached Option Agreement.

     ADJUSTMENTS UPON RECAPITALIZATION: The Option contains provisions which
affect your rights in the event of stock splits, stock dividends, mergers and
other major corporate reorganizations. See Section 6 of the attached Option
Agreement.

     WAIVER: By signing this Certificate, you will be agreeing to all of the
terms of the Option Agreement, including those not summarized in this
Certificate. You will waive your rights to options or stock which may otherwise
have been promised to you. See Section 7 of the attached Option Agreement.

     WITHHOLDING: The Company may require you to make any arrangements necessary
to insure the proper withholding of any amount of tax, if any, required to be
withheld by the Company as a result of the exercise of the Option. See Section
10 of the attached Option Agreement.


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                                    AGREEMENT

     3D Systems Corporation, a Delaware corporation, and Optionee each hereby
agrees to be bound by all of the terms and conditions of the Stock Option
Agreement (Non-Statutory Stock Option) which is attached hereto as Annex I and
incorporated herein by this reference as if set forth in full in this document.

DATED: JULY 1, 1999
      --------------------

                             3D SYSTEMS CORPORATION


                             By:/S/ ARTHUR B. SIMMS
                                -----------------------------------
                             Its: Chief Executive Officer

                             OPTIONEE


                             Name:/S/ WALTER LOEWENBAUM
                                  ---------------------------------


                             --------------------------------------
                             (Please print your name exactly as you
                             wish it to appear on any stock certificates
                             issued to you upon exercise of the Option)


                                     Page 3
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                                     ANNEX I

                             STOCK OPTION AGREEMENT

                          (NON-STATUTORY STOCK OPTION)

     This STOCK OPTION AGREEMENT (this "OPTION AGREEMENT") is made and entered
into on the execution date of the Option Certification to which it is attached
(the "CERTIFICATE"), by and between 3D Systems Corporation, a Delaware
corporation (the "COMPANY"), and the employee of the Company named in the
Certificate ("OPTIONEE").

     The Board of Directors of the Company (the "BOARD") has authorized the
grant to Optionee of a non-statutory stock option to purchase shares of the
Company's Common Stock, par value $0.001 per share (the "COMMON STOCK"), upon
the terms and subject to the conditions set forth in this Option Agreement.

     The Company and Optionee agree as follows:

1.   GRANT OF OPTION.

     The Company hereby grants to Optionee the right and option (the "OPTION"),
upon the terms and subject to the conditions set forth in this Option Agreement,
to purchase all or any portion of that number of shares of the Common Stock (the
"SHARES") set forth in the Certificate, at the Option exercise price set forth
in the Certificate (the "EXERCISE PRICE").

2.   TERM OF OPTION.

     The Option shall terminate and expire on the Option Expiration Date set
forth in the Certificate, unless sooner terminated as provided herein. In no
event shall the Option be exercisable after the expiration of ten years from the
date it was granted.

3.   EXERCISE PERIOD.

     (a) Subject to the provisions of Sections 3(b) and 5 of this Option
Agreement, the Option shall become exercisable (in whole or in part) upon and
after the dates set forth or referred to under the caption "Exercise Schedule"
in the Certificate. The installments shall be cumulative; I.E., the Option may
be exercised, as to any or all Shares covered by an installment, at any time or
times after the installment first becomes exercisable and until expiration or
termination of the Option.

     (b) Notwithstanding anything to the contrary contained in this Option
Agreement, the Option may not be exercised, in whole or in part, unless and
until any then-applicable requirements of all federal, state and local laws and
regulatory agencies shall have been fully complied with to the satisfaction of
the Company and its counsel. In addition, if the Company believes that Optionee
has committed an act of misconduct, including an act of embezzlement, fraud,
nonpayment of any obligation owed to the Company or any subsidiary, breach of
fiduciary duty or deliberate disregard of the Company's rules resulting in loss,
damage or injury to the Company, any unauthorized disclosure of trade secrets or
confidential information of the Company, any conduct constituting unfair
competition, or the inducement of any customer of the Company to breach a
contract with


<PAGE>


the Company), the Company may suspend the Optionee's rights under the Option
pending a determination by the Board of Directors, which shall have the right,
as therein provided, to terminate the Option.

4.   EXERCISE OF OPTION.

     There is no obligation to exercise the Option, in whole or in part. The
Option may be exercised, in whole or in pan, only by delivery to the Company of:

     (a) written notice of exercise in form and substance identical to Exhibit
"A" attached to this Option Agreement stating the number of shares of Common
Stock then being purchased (the "PURCHASED SHARES");

     (b) the Exercise Price for each Purchased Share shall be paid in full upon
exercise and shall be payable in cash in United States dollars (including check,
bank draft or money order); PROVIDED, HOWEVER that in lieu of cash the person
exercising the Option may pay the Exercise Price in whole or in part by
delivering to the Company shares of the Common Stock having a fair market value
on the date of exercise of the Option, determined as provided in Section 4(c),
equal to the Exercise Price for the Shares being purchased; except that (i) any
portion of the Exercise Price representing a fraction of a Share shall in any
event be paid in cash and (ii) no shares of the Common Stock which have been
held for less than six months may be delivered in payment of the Exercise Price
of an Option. Delivery of shares may also be accomplished through the effective
transfer to the Company of shares held by a broker or other agent. The Company
will also cooperate with any person who participates in a cashless exercise
program of a broker or other agent under which all or part of the shares
received upon exercise of the Option are sold through the broker or other agent
or under which the broker or other agent makes a loan to such person.
Notwithstanding the foregoing, the exercise of the Option shall not be deemed to
occur and no shares of Common Stock will be issued by the Company upon exercise
of the Option until the Company has received payment of the Exercise Price in
full. The date of exercise of an Option shall be determined under procedures
established by the Committee.

     (c) If payment is made, in whole or in part, by transfer to the Corporation
of issued and outstanding shares of Common Stock, the value of such shares shall
be the mean between the following prices, as applicable, for the date as of
which fair market value is to be determined as quoted in THE WALL STREET JOURNAL
(or in such other reliable publication as the Company, in its discretion, may
determine to rely upon): (i) if the Common Stock is listed on a United States
securities exchange, the highest and lowest sales prices per share of Common
Stock for such date on the principal United States securities exchange on which
the Common Stock is listed, or (ii) if the Common Stock is not listed on any
such exchange, the highest and lowest sales prices per share of the Common Stock
for such date on the Nasdaq National Market or any successor system then in use.
If there are no such sale price quotations for the date as of which fair market
value is to be determined but there are such sale price quotations within a
reasonable period both before and after such date, then fair market value shall
be determined by taking an average of the means between the highest and lowest
sales prices per share of the Common Stock as so quoted on the nearest date
before and the nearest date after the date as of which fair market value is to
be determined. If there are no such sale price quotations on or within a
reasonable period both before and after the date as of which fair market value
is to be determined, then fair market value of the Common Stock shall be the
mean between the bona fide bid and asked prices per share of Common Stock as so
quoted for


                                     Page 2
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such date on Nasdaq, or if none, the average of the means between such bid and
asked prices on the nearest trading date before and the nearest trading date
after the date as of which fair market value is to be determined, if both such
dates are within a reasonable period. If the fair market value of the Common
Stock cannot be determined on the basis set forth above, the Committee shall in
good faith determine the fair market value of the Common Stock as of such date.

5.   TERMINATION OF EMPLOYMENT.

     (a) If Optionee shall cease to have a Relationship (as defined below) with
the Company, or any direct or redirect subsidiary of the Company, (other than as
the result of the transfer of employment of Optionee to another corporation
which is the Company, or any direct or indirect subsidiary of the Company) for
any reason other than retirement, death or permanent disability (a "TERMINATING
EVENT"), Optionee shall have the right, subject to the provisions of Section
5(b) below, to exercise the Option at any time following such Terminating Event
until the earliest to occur of (x) 90 days following the date of such
Terminating Event and (y) the expiration of the term of this Option as set forth
in Section 2 of this Option Agreement. For purposes of this Option Agreement,
Optionee shall have a "RELATIONSHIP" with the Company so long as Optionee is
either a member of the Board of Directors of the Company, a consultant of the
Company, or an employee of the Company. The Option may be exercised following a
Terminating Event only to the extent exercisable as of the date of the
Terminating Event. To the extent unexercised at the end of the period referred
to above, the Option shall terminate. The Committee, in its sole and absolute
discretion, shall determine whether (i) authorized leaves of absence shall
constitute termination of Optionee's Relationship with the Company and (ii)
Optionee's Relationship with the Company has terminated, for purposes of this
Option Agreement.

     (b) Notwithstanding the provisions of Section 5(a) above, if the Company
believes that Optionee has committed an act of misconduct as described below,
the Company may suspend Optionee's rights under the Option pending a
determination by the Board of Directors of the Company. If the Board of
Directors determines that Optionee has committed an act of embezzlement, fraud,
nonpayment of any obligation owed to the Company or any subsidiary, breach of
fiduciary duty or deliberate disregard of the Company's rules resulting in loss,
damage or injury to the Company, or if an Optionee makes an unauthorized
disclosure of trade secret or confidential information of the Company, engages
in any conduct constituting unfair competition, or induces any customer of the
Company to breach a contract with the Company, neither the Optionee nor his or
her estate shall be entitled to exercise any rights whatsoever with respect to
the Option. In making such determination, the Board of Directors shall act
fairly and shall give the Optionee a reasonable opportunity to appear and
present evidence on his behalf at a hearing before a committee of the Board of
Directors; and if the Optionee is an "employee" under Rule 16a-l(f) of the
Rules and Regulations of the Securities and Exchange Commission under the
Securities Exchange Act of 1934, as amended, the determination of the Board of
Directors shall be subject to the approval of the Committee.

     (c) If, by reason of retirement, death or disability (a "SPECIAL
TERMINATING EVENT"), Optionee shall cease to have a Relationship with the
Company or any direct or indirect subsidiary of the Company (other than as the
result of the transfer of employment of Optionee to another corporation which is
the Company, or any direct or indirect subsidiary of the Company), then
Optionee, Optionee's executors or administrators or any person or persons
acquiring the Option directly from Optionee by bequest or inheritance, shall
have the right to exercise the Option (i) in


                                     Page 3
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the event of Optionee's disability, within twelve months following the date of
such Special Terminating Event, or (ii) in the event of Optionee's retirement,
or in the event of Optionee's death, within eighteen months of either Special
Terminating Event. The option may be exercised following a Special Terminating
Event only to the extent exercisable at the date of the Special Terminating
Event. To the extent unexercised at the end of the period referred to above, the
Option shall terminate.

     (d) For purposes of this Option Agreement, "disability" shall mean total
and permanent disability as defined in Section 22(e)(3) of the Internal Revenue
Code of 1986, as amended (the "CODE"). Optionee shall not be considered
permanently disabled unless he furnishes proof of such disability in such form
and manner, and at such times, as the Committee may from time to time require.

6.   ADJUSTMENTS UPON RECAPITALIZATION.

     In the event of any change in the outstanding shares of the Common Stock or
other securities then subject to this option by reason of any stock split,
reverse stock split, stock dividend, recapitalization, merger, consolidation,
combination or exchange of shares or other similar corporate change, or if the
outstanding securities of the class then subject to this Agreement are exchanged
for or converted into cash, property or a different kind of securities, or if
cash, property or securities are distributed in respect of such outstanding
securities (other than a regular cash divided) then, unless the terms of such
transaction shall otherwise provide, such equitable adjustments shall be made by
the Board, or the Committee, in the Option (including, without limitation,
appropriate and proportionate adjustments to the number and type of shares or
other securities or cash or other property that may be acquired pursuant to
exercise of the Option); and any such adjustments made by the Board or the
Committee shall be final, binding and conclusive for any and all purposes.

7.   WAIVER OF RIGHTS TO PURCHASE STOCK.

     By signing this Option Agreement, Optionee acknowledges and agrees that
neither the Company nor any other person or entity is under any obligation to
sell or transfer to Optionee any option or equity security of the Company, other
than the shares of Common Stock subject to the Option and any other right or
option to purchase Common Stock which was previously granted in writing to
Optionee by the Committee (or the Board). By signing this Option Agreement,
Optionee specifically waives all rights which he or she may have had prior to
the date or this Option Agreement (other than any other right or option to
purchase Common Stock which was previously granted in writing to Optionee by the
Committee or the Board) to receive any option or equity security of the Company.

8.   NO RIGHTS AS SHAREHOLDER.

     Except as provided in Section 6 of this Option Agreement, Optionee shall
have no rights as a shareholder with respect to the Shares until the date of the
issuance to Optionee of a stock certificate or stock certificates evidencing
such Shares. Except as may be provided in Section 6 of this Option Agreement, no
adjustment shall be made for dividends (ordinary or extraordinary, whether in
cash, securities or other property) or distributions or other rights for which
the record date is prior to the date such stock certificate is issued.


                                     Page 5
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9.   MODIFICATION.

     The Committee (or the Board) may modify, extend or renew the Option or
accept the surrender of, and authorize the grant of a new option in substitution
for, the Option (to the extent not previously exercised); PROVIDED, that a
modification of the Option shall be effective only with the consent of the
Optionee.

10.  WITHHOLDING.

     The Company shall be entitled to require as a condition of delivery of any
Purchased Shares upon exercise of any Option that the Optionee agree to remit,
at the time of such delivery or at such later date as the Company may determine,
an amount sufficient to satisfy all federal, state and local withholding tax
requirements relating thereto, and Optionee agrees to take such other action
required by the Company to satisfy such withholding requirements.

11.  CHARACTER OF OPTION.

     The Option is not intended to qualify as an "incentive stock option" as
that term is defined in Section 422 of the Code.

12.  GENERAL PROVISIONS.

     (a) FURTHER ASSURANCES. Optionee shall promptly take all actions and
execute all documents requested by the Company which the Company deems to be
reasonably necessary to effectuate the terms and intent of this Option
Agreement.

     (b) NOTICES. All notices, requests, demands and other communications under
this Option Agreement shall be in writing and shall be given to the parties
hereto as follows:

                      1. If to the Company, to:
                         3D Systems Corporation
                         26081 Avenue Hall
                         Valencia, CA 91355
                         Attention: General Counsel

                      2. If to Optionee, to the address
                         set forth in the records of the Company,

or at such other address or addresses as may have been furnished by such either
party in writing to the other party hereto. Any such notice, request, demand or
other communication shall be effective (i) if given by mail, 72 hours after such
communication is deposited in the mail by first-class certified mail, return
receipt requested, postage prepaid, addressed as aforesaid; or (ii) if given by
any other means, when delivered at the address specified in this subparagraph
(b).

     (c) TRANSFER OF RIGHTS UNDER THIS OPTION AGREEMENT. The Company may at any
time transfer and assign its rights and delegate its obligations under this
Option Agreement to any other person, corporation, firm or entity, including its
employees, directors and stockholders, with or without consideration.


                                     Page 5
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     (d) OPTION NON-TRANSFERABLE. Optionee may not sell, transfer, assign or
otherwise dispose of the Option except by will or the laws of descent and
distribution, and options may be exercised during the lifetime of Optionee only
by Optionee or by his or her guardian or legal representative.

     (e) MARKET STAND-OFF. In the event of an underwritten public offering by
the Company of its equity securities pursuant to an effective registration
statement filed under the Securities Act of 1933, as amended, Optionee shall not
sell, make any short sale of, loan, hypothecate, pledge, grant any option for
the repurchase of, or otherwise dispose or transfer for value, or otherwise
agree to engage in any of the foregoing transactions with respect to any shares
of Common Stock without the prior written consent of the Company or its
underwriters, for such period of time from and after the effective date of such
registration statement as may be requested by the Company or such underwriters
(the "MARKET STAND-OFF"); provided, however, that in no event shall such period
exceed 180 days.

     (f) SUCCESSORS AND ASSIGNS. Except to the extent specifically limited by
the terms and provisions of this Option Agreement, this Option Agreement shall
be binding upon and inure to the benefit of the parties hereto and their
respective successors, assigns, heirs and personal representatives.

     (g) GOVERNING LAW. THIS OPTION AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED
IN ACCORDANCE WITH THE LAWS OF THE STATE OF CALIFORNIA APPLICABLE TO CONTRACTS
MADE IN, AND TO BE PERFORMED SOLELY WITHIN, THAT STATE.

     (h) MISCELLANEOUS. Titles and captions contained in this Option Agreement
are inserted for convenience of reference only and do not constitute a part of
this Option Agreement for any other purpose.

     The Signature Page to this Option Agreement consists of the last page of
the Certificate.


                                     Page 6
<PAGE>


                                   EXHIBIT "A"

                               NOTICE OF EXERCISE

                 (TO BE SIGNED ONLY UPON EXERCISE OF THE OPTION)

3D Systems Corporation

     The undersigned, the holder of the enclosed Stock Option Agreement
(Non-Statutory Stock Option), hereby irrevocably elects to exercise the purchase
rights represented by the Option and to purchase thereunder _______* shares of
Common Stock of 3D Systems Corporation (the "COMPANY"), and herewith encloses
payment of $____________ and/or ___________ shares of the Company's Common Stock
in full payment of the purchase price of such shares being purchased.

Dated: ______________________

                               -----------------------------------------------
                               Signature must conform in all respects to
                               name of holder as specified on the face of the
                               Option)

                               -----------------------------------------------
                               (Please Print Name)

                               -----------------------------------------------
                               (Address)

     *Insert here the number of shares called for on the face of the Option (or,
in the case of a partial exercise, the number of shares being exercised), in
either case without making any adjustment for additional CoIranon Stock of the
Company, other securities or property which, pursuant to the adjustment
provisions of the Option, may be deliverable upon exercise.