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                                                                   Exhibit 10.5


                  AMENDED AND RESTATED REVOLVING CREDIT NOTE
                  ------------------------------------------

US $6,719,770.39                                             December 21, 2006
                                                           St. Louis, Missouri

     For value received, the undersigned, Zoltek Companies, Inc., a Missouri
corporation, Zoltek Corporation, a Missouri corporation, Zoltek Properties,
Inc., a Missouri corporation, and Engineering Technology Corporation, a
Missouri corporation (individually and collectively hereinafter "Borrowers";
all references to "Borrowers" or "Borrower" shall mean each and all of the
Borrowers), hereby jointly and severally promise to pay to the order of
Southwest Bank of St. Louis (the "Bank"), in lawful money of the United States
of America, the principal sum of Six Million Seven Hundred Nineteen Thousand
Seven Hundred Seventy and 39/100 Dollars ($6,719,770.39), or if less, the
amount outstanding under Section 2.02 of the Credit Agreement (as hereinafter
                         ------------
defined), together with interest from the date hereof at the rate provided for
in the Credit Agreement. Principal and interest of this Note shall be payable
at the time or times provided in Section 3 of the Credit Agreement.
                                 ---------

     This Amended and Restated Revolving Credit Note (this "Note") is the
Revolving Credit Note referred to in, and is issued pursuant to, that certain
Credit Agreement among the Borrowers, Cape Composites, Inc., Hardcore
Composites Operations, LLC and the Bank dated as of May 11, 2001, as amended
by that certain First Amendment to Credit Agreement dated as of February 13,
2003, that certain Second Amendment to Credit Agreement dated as of January
13, 2004, and that certain Third Amendment to Credit Agreement of even date
herewith (as further amended or otherwise modified from time to time, the
"Credit Agreement"), and is entitled to all of the benefits and security of
the Credit Agreement. All of the terms, covenants and conditions of the Credit
Agreement and all other instruments evidencing or securing the indebtedness
hereunder are hereby made a part of this Note and are deemed incorporated
herein in full. All capitalized terms used herein, unless otherwise
specifically defined in this Note, shall have the meanings ascribed to them in
the Credit Agreement.

     This Note is secured by the Collateral described in the Credit Agreement.

     Interest hereunder shall be computed on, the basis of actual days elapsed
over the period of a 360-day year. Upon or after the occurrence and during the
continuation of any Event of Default, the outstanding principal balance of
this Note shall bear interest at a variable rate per annum equal to the
Default Rate until the principal balance of this Note is paid in full.

     In no contingency or event whatsoever, whether by reason of advancement
of the proceeds hereof or otherwise, shall the amount paid or agreed to be
paid to the Bank for the use, forbearance or detention of money advanced
hereunder exceed the highest lawful rate permissible under any law which a
court of competent jurisdiction may deem applicable hereto.

     The Borrowers may prepay this Note, in whole or in part, at any time
without premium or penalty.

     The termination of the Credit Agreement or the occurrence and continuance
of an Event of Default shall entitle the Bank, at its option, to declare the
then outstanding principal balance and accrued interest hereon to be, and the
same shall thereupon become, immediately due and payable without notice to or
demand upon the Borrowers, all of which the Borrowers hereby expressly waive.


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     Time is of the essence of this Note. To the fullest extent permitted by
applicable law, the Borrowers, for themselves and their successors and
assigns, expressly waive presentment, demand, protest and notice of dishonor,
and hereby consent to any extensions of time, renewals, release of any parties
to or guarantors of this Note, waivers and any other modifications that may be
granted or consented to by the Bank from time to time in respect of the time
of payment or any other provision of this Note.

     Wherever possible each provision of this Note shall be interpreted in
such a manner as to be effective and valid under applicable law, but if any
provision of this Note shall be prohibited or invalid under applicable law,
such provision shall be ineffective to the extent of such prohibition or
invalidity without invalidating the remainder of such provision or remaining
provisions of this Note. No delay or failure on the part of the Bank in the
exercise of any right or remedy hereunder shall operate as a waiver thereof,
nor as an acquiescence in any default, nor shall any single or partial
exercise by the Bank of any right or remedy preclude any other right, or
remedy. The Bank, at its option, may enforce its rights against any collateral
securing this Note without enforcing its rights against the Borrowers, any
guarantor of the indebtedness evidenced hereby or any other property or
indebtedness due or to become due to the Borrowers. The Borrowers agree that,
without releasing or impairing the Borrowers' liability hereunder, the Bank
may at any time release, surrender, substitute or exchange any collateral
securing this Note and may at any time release any party primarily or
secondarily liable for the indebtedness evidenced by this Note.

     This Note is a restated and amended version of that certain Revolving
Credit Note dated as of May 11, 2001, executed by the Borrowers, Hardcore
Composites Operations, LLC and Cape Composites, Inc. in favor of Bank in the
original principal amount of $10,000,000.00, that certain Amended and Restated
Revolving Credit Note dated as of February 13, 2003, executed by Borrowers and
Cape Composites, Inc. in favor of Bank in the original principal amount of
$5,000,000.00, that certain Amended and Restated Revolving Credit Note dated
as of January 13, 2004, executed by Borrowers and Cape Composites, Inc. in
favor of Bank in the original principal amount of $5,000,000.00, and that
certain Amended and Restated Revolving Credit Note dated as of December 27,
2004, executed by Borrowers and Cape Composites, Inc. in favor of Bank in the
original principal amount of $5,500,000.00, and shall not constitute a
cancellation of the principal amount of such note evidenced thereby.

     This Note shall be governed by, and construed and enforced in accordance
with, the internal laws of the State of Missouri.

     BORROWERS HEREBY WAIVE ANY RIGHT TO TRIAL BY JURY (WHICH BANK ALSO
WAIVES) IN ANY ACTION, SUITE, PROCEEDING OR COUNTERCLAIM OF ANY KIND ARISING
OUT OF OR RELATING TO THIS NOTE OR ANY OF THE LOAN DOCUMENTS, THE COLLATERAL,
OR BANK'S CONDUCT IN RESPECT OF ANY OF THE FOREGOING.

     IN WITNESS WHEREOF, the Borrowers have caused this Note to be executed
and delivered by their respective duly authorized representatives as of the
date first above written.

                                  ZOLTEK COMPANIES, INC.

                                  By:  /s/ Zsolt Rumy
                                     -----------------------------------------
                                  Name: Zsolt Rumy
                                       ---------------------------------------
                                  Title: President
                                        --------------------------------------


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                                  ZOLTEK CORPORATION

                                  By:   /s/ Zsolt Rumy
                                     -----------------------------------------
                                  Name: Zsolt Rumy
                                       ---------------------------------------
                                  Title: President
                                        --------------------------------------


                                  ZOLTEK PROPERTIES, INC.

                                  By:   /s/ Zsolt Rumy
                                     -----------------------------------------
                                  Name: Zsolt Rumy
                                       ---------------------------------------
                                  Title: President
                                        --------------------------------------


                                  ENGINEERING TECHNOLOGY CORPORATION

                                  By:   /s/ Zsolt Rumy
                                     -----------------------------------------
                                  Name: Zsolt Rumy
                                       ---------------------------------------
                                  Title: President
                                        --------------------------------------


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