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                                                                   EXHIBIT 10.12
                                 July 9th, 2004

Board of Directors
American Building Control, Inc.
1301 Waters Ridge Drive
Lewisville, Texas 75057

Gentlemen:

      Subject to the conditions set forth in the next sentence, I hereby resign
from all positions as an officer of American Building Control, Inc. (the
"Company") and its affiliates, and hereby resign from my employment with the
Company and its affiliates, all effective as of the end of the day on Friday,
July 9, 2004. This resignation is conditioned on (i) the agreement of the
Company and its Board of Directors to treat this resignation as a termination
without cause by the Company for purposes of my employment letter with the
Company dated December 18, 2003, and (ii) the approval by the Company's Board of
Directors of the Company's proposal to me set forth in the letter of July 9,
2004, sent to me by Kenneth L. Stewart of Fulbright & Jaworski L.L.P., as
counsel to the Company.

                                                            Very truly yours,

                                                            /s/ Danny Mills

                                                            Danny Mills

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                          FULBRIGHT & JAWORSKI L.L.P.
                   A REGISTERED LIMITED LIABILITY PARTNERSHIP
                          2200 Ross AVENUE, SUITE 2800
                            DALLAS, TEXAS 75201-2784
                               WWW.FULBRIGHT.COM

KENNETH L. STEWART                                  DIRECT DIAL: (214) 855-8060
PARTNER                                               TELEPHONE: (214) 855-8000
KSTEWART@FULBRIGHT.COM                                FACSIMILE: (214) 855-82OO

                                  July 9, 2004

Mr. Danny Mills
122 Fox Hall Cove
San Antonio, TX 78213

      Re:   Termination of Employment with American Building Control, Inc. (the
            "Company")

Dear Danny:

      This is a revised version of the letter I sent you yesterday. The changes
in this letter are a clarification added in paragraph 4 and the revision in
paragraph 5 that you and Carlo Loi discussed.

      I have reviewed the documents regarding your performance options and bonus
and discussed them with Carlo Loi. Carlo has asked me to communicate to you in
writing the Company's proposal regarding your termination of employment with the
Company. This proposal is subject to approval by the Board of Directors of the
Company, which Carlo will seek to obtain as soon as possible after you and he
reach agreement on the proposal.

      1.    Termination of your positions as an officer of the Company and all
            of its affiliates and termination of your employment with the
            Company and all of its affiliates will be effective at the end of
            the day on Friday, July 9, 2004. If you resign from your officer
            positions and employment effective as of the time stated above, the
            Company will treat your resignation as a termination without cause
            for purposes of your employment letter dated December 18, 2003.

      2.    In accordance with the terms of your employment letter dated
            December 18, 2003, your initial grant of options to acquire 250,000
            shares of the Company's common stock under the Company's 2002
            Incentive Stock Option Plan (as described in paragraph 4(a)(i) of
            your employment letter) shall vest in their entirety effective as of
            your termination of employment on Friday, July 9, 2004.

      3.    Pursuant to paragraph 5 of your employment letter, you will be
            entitled to be paid severance compensation in the total amount of
            $90,000, payable over six months beginning immediately after your
            termination date set forth above, in the same manner as payments of
            compensation were made to you prior to the date of termination of
            your employment.

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July 9, 2004
Mr. Danny Mills
Page 2

      4.    To the extent permitted by the plans, during such six-month period
            described in paragraph 3 above, you will continue participation in
            the Company's health and welfare plans on the same basis (including
            payments by the Company) as prior to the date of termination of your
            employment.

      5.    With respect to your performance stock options and your cash
            incentive bonus plan, the Company will (a) review these items after
            December 31, 2004, in the normal course of the Company's review of
            these items for other executives of the Company, (b) determine
            whether you would have been entitled to any cash payments or
            continuing stock options under the terms of your option grant and
            the Company's 2004 Management Incentive Plan based on the Company's
            performance in 2004 had your employment with the Company continued
            through December 31,2004, and (c) pay a cash bonus to you, or
            continue stock options for you, as the case may be, in a pro rata
            (50%) portion of the amounts, if any, you would have received under
            your option grant and the Company's 2004 Management Incentive Plan
            based on the Company's performance in 2004 had your employment with
            the Company continued through December 31, 2004. Notwithstanding the
            provisions of paragraph 2 of your Stock Option Agreement for your
            Performance Option for 2004, the portion, if any, of the option
            described in such agreement that is finally determined to be awarded
            to you in accordance with the provisions of paragraph 1 of such
            agreement shall vest and become exercisable immediately on the date
            the committee that administers the option determines the total
            shares, if any, under the option that have been awarded in
            accordance with paragraph 1 of such agreement.

      Enclosed with this letter is a draft of a letter that you could use as a
resignation letter if you find the proposal set forth above to be acceptable.

      You should contact Carlo Loi directly regarding how you desire to proceed.

                                                         Very truly yours.

                                                         /s/ Kenneth L. Stewart

                                                         Kenneth L. Stewart

KLS/gb

Enclosure
cc: Mr. Carlo Loi (via e-mail)