EXHIBIT 3.12

AMENDED AND RESTATED

OPERATING AGREEMENT FOR

NEW MILLENNIUM BUILDING SYSTEMS, LLC

This Amended and Restated Operating Agreement is made and entered into by and between Steel Dynamics, Inc., as the sole member of New Millennium Building Systems, LLC, an Indiana limited liability company (the “Company”) and the Company.

Preliminary Statement

New Millennium Building Systems, LLC, an Indiana limited liability company (the “Company”), was organized on June 25, 1999.  The Company was formed under the laws of the State of Indiana by the filing of Articles of Organization (the “Original Articles”) pursuant to the Indiana Business Flexibility Act (the “Act”) on behalf of Steel Dynamics, Inc., New Process Steel Holding Co., Inc., Joseph E. Maupin, Bert D. Hollman, Douglas D. Lang and Ariail R. Smith as the Initial Members.  Effective September 23, 1999, the Initial Members entered into an Operating Agreement (“Original Operating Agreement”) to govern certain aspects of the operations of the Company and to set forth the rights and obligations of the successors and assigns.  Effective February 25, 2000, the then existing members entered into a First Amendment to Operating Agreement (“First Amendment”), effective January 1, 2002, the then existing members entered into a Second Amendment to Operating Agreement (“Second Amendment”), effective July 1, 2002, the then existing members entered into a Third Amendment to Operating Agreement (“Third Amendment”), and effective December 31, 2002, the then existing members entered into a Fourth Amendment to Operating Agreement (“Fourth Amendment”).  The Original Operating Agreement, together with the First Amendment, the Second Amendment, the Third Amendment and the Fourth Amendment are hereinafter collectively referred to as the “Company Operating Agreement.”

Effective February 21, 2003, New Process Steel Holding Co., Inc. transferred all of its rights, title and interest in and to its Series A membership Units of the Company to Steel Dynamics, Inc., at which time Steel Dynamics, Inc. then held all outstanding Series A Units.  Effective March 31, 2003, all the holders of the Series B membership Units of the Company transferred all of their rights, title and interest in and to their respective Series B Units to Steel Dynamics, Inc., at which time Steel Dynamics, Inc. became the sole member of the Company.

Steel Dynamics, Inc., as the sole member of the Company (herein the “Member”) now desires to adopt this Amended and Restated Operating Agreement to amend certain aspects of the Company Operating Agreement and to restate the terms under which the Company will be governed and the rights and obligations of its members, including any assignee or substitute member, and their respective successors and assigns.

In consideration of the mutual covenants and agreements contained in this Agreement, and intending to be legally bound thereby, the undersigned parties agree to the following terms and conditions.

Article 1Preliminary Provisions

1.1EFFECTIVE DATE OF AGREEMENT; ENFORCEABILITY.

The effective date of this Agreement (the “Effective Date”) shall be April 1, 2006.

1.2COMPANY’S NAME, PURPOSE, ETC.

The Company’s name, purpose, registered agent, registered office, duration and form of management shall be as set forth in the Articles.

1.3PRINCIPAL PLACE OF BUSINESS OF COMPANY.

The Company’s principal place of business shall be 6714 Point Inverness Way, Suite 200, Fort Wayne, IN  46804.  The Member of the Company may change the Company’s principal place of business from time to time in the Member’s sole discretion.

1.4RESERVATION OF MANAGEMENT OF COMPANY TO MEMBER.

The management of the Company is reserved to the Member.

1.5LIMITED LIABILITY OF MEMBER.

(a)The Member shall not be personally obligated to any third party for any debt, obligation or liability of the Company solely by reason of being a member.

(b)The Member shall be liable for its conduct in its individual capacity as provided by law.

1.6ADMISSION OF ADDITIONAL MEMBERS.

Whether additional members shall be admitted as members of the Company shall be in the sole discretion of the Member.

1.7AMENDMENT OF AGREEMENT IF COMPANY HAS MULTIPLE MEMBERS

If, at any time, the Company has two or more members, the members shall, with reasonable promptness, make all amendments to this Agreement necessary to reflect their agreement concerning the allocation of the Company’s profits and losses, the allocation of management rights, and other appropriate matters.

1.8ANNUAL ACCOUNTING PERIOD OF COMPANY.

The Company’s annual accounting period for financial and tax purposes shall be the calendar year.

1.9COMPANY METHOD OF ACCOUNTING.

The COMPANY shall use the accrual method of accounting, consistent with the accounting method used by the Member.

1.10EFFECT OF ACT.

Except as otherwise provided in this Agreement or by law, the business and internal affairs of the Company shall be governed by the Act as in effect on the Effective Date.

1.11RELATION OF AGREEMENT TO ARTICLES.

If there is any conflict between the provisions of this Agreement and those of the Articles, the provisions of this Agreement shall prevail.

1.12QUALIFICATION IN OTHER JURISDICTIONS.

Before conducting business on a regular basis in any jurisdiction other than this State, the Company shall file all forms and shall do all other things required under the laws, including the tax laws, of that jurisdiction in order to conduct that business.

Article 2CAPITAL CONTRIBUTIONS AND LOAN

2.1CONTRIBUTIONS OF CASH AND NON-CASH PROPERTY.

The initial capital contribution to the Company made by the Member as of the Effective Date is reflected on Exhibit “A” which is attached hereto and made a part hereof (the “Initial Contribution”).

2.2NO DUTY TO MAKE ADDITIONAL CONTRIBUTIONS.

In addition to the Initial Contribution, the Member may, but shall have no duty to, make additional contributions to the Company.

2.3LOANS BY MEMBER TO COMPANY.

The Member may, in its sole discretion, make loans to the Company in amounts and upon terms determined by the Member.

Article 3ALLOCATIONS AND DISTRIBUTIONS OF COMPANY PROFITS

3.1ALLOCATIONS OF PROFITS AND LOSSES AND ALLOCATIONS OF DISTRIBUTIONS.

Only the Member shall be entitled to allocations of Company profits and losses, to allocations of distributions of Company profits and other Company assets and to distributions of Company profits and other assets.  No other person shall have any right to any such allocations or distributions.

3.2DECISIONS CONCERNING ALLOCATIONS, ETC.

It shall be within the sole and exclusive discretion of the Member to decide:

(a)Whether to make allocations of Company profits and losses to the Member;

(b)Whether to make allocations of distributions of profits and other assets to the Member;

(c)Whether to make distributions of profits and other assets to the Member; and

(d)When and in what amounts to make any such allocation or distribution;

PROVIDED, that the Company shall make no such distribution to the extent that, immediately after the distribution, the Company’s liabilities would exceed its assets.

Article 4COMPANY MANAGEMENT

4.1DECISION-MAKING.

The Member, in the Member’s sole discretion, shall have the exclusive right to make decisions relating to the business and internal affairs of the Company.

4.2SIGNING OF CONTRACTS, ETC.

The Member, in the Member’s sole discretion, shall have the exclusive right, power and authority to sign contracts on behalf of the Company and otherwise bind the Company with third parties, and to authorize individuals to take such action for and on behalf of the Company.

4.3NO DUTY TO RECORD DECISIONS, ETC.

The Member in the Member’s capacity as a member shall have no duty to record in writing or otherwise any decision in the Member’s capacity as a member, and the Member’s failure to make any such record shall not impair the validity of any such decision.

4.4DESIGNATION OF OFFICERS AS PRESIDENT, ETC.

In exercising the Member’s rights, powers and authority hereunder, one or more duly authorized officers of the Member may use the title “President,” “Vice President” or any other title that the Member shall determine such designated officer or officers of Member should use from time to time.

4.5INDEMNIFICATION OF MEMBER.

The Company shall fully indemnify the Member for any claim against the Member in the Member’s capacity as a managing member.

Article 5TRANSFERS AND PLEDGES OF COMPANY MEMBERSHIP RIGHTS AND INTERESTS

5.1TRANSFERS OF MEMBERSHIP RIGHTS - IN GENERAL.

The Member, in the Member’s sole discretion, may transfer (whether by sale, gift or otherwise) all or any part of the Member’s membership rights, including economic and non-economic rights, to any person at any time.  The Member may make any such transfer under any terms and conditions that the Member deems appropriate.

5.2PLEDGES.

The Member shall have exclusive and absolute discretion to pledge all or any part of the Member’s membership rights to any person at any time as collateral for any debt of the Member.  The Member may make any such pledge under any terms and conditions that the Member deems appropriate.

Article 6COMPANY BOOKS OF ACCOUNTS, REPORTS, ETC.

The Company shall maintain on a current basis accurate books of account in accordance with financial standards normally applied to business organizations generally similar to the Company in size and business activities.

Article 7DISSOLUTION.

7.1DEFINITION OF DISSOLUTION, WINDING UP AND LIQUIDATION.

For purposes of this Agreement:

(a)Dissolution.  The dissolution of the Company shall mean the cessation of its normal business activities and the beginning of the process of winding it up and liquidating it.

(b)Winding Up.  The winding up of the Company shall mean the process of concluding its existing business activities and internal affairs and preparing for its liquidation.

(c)Liquidation.  The liquidation of the Company shall mean the sale or other disposition of its assets and the distribution of its assets (or the distribution of the proceeds of the sale or other disposition of its assets) to its creditors and to the members.

7.2DISSOLUTION OF COMPANY.

The Member, in the Member’s sole and absolute discretion, may determine whether and when to dissolve the Company.  The Company shall be dissolved immediately upon the Member’s deciding to dissolve it.

7.3FILING OF CERTIFICATE OF DISSOLUTION.

Upon determining to dissolve the Company, the Member shall file a certificate of dissolution with the Secretary of State.

7.4DATE OF TERMINATION OF LEGAL EXISTENCE OF COMPANY.

The certificate of dissolution shall set forth the effective date of the cancellation of the Company’s Articles.  On that date, the legal existence of the Company shall terminate.

7.5WINDING UP AND LIQUIDATION OF COMPANY; DISTRIBUTION OF COMPANY ASSETS.

Promptly after determining to terminate the legal existence of the Company, the Member shall wind up its business and internal affairs, shall liquidate it, and shall distribute its assets to the Member and to creditors as required by the Act.

7.6SATISFACTION OF COMPANY’S KNOWN AND UNKNOWN DEBTS.

In connection with the winding-up of the Company, the Member shall take all appropriate measures:

(a)To comply with applicable federal and state tax laws and other laws relating to entity dissolutions; and

(b)To the extent possible under the laws of this State, to bar known and unknown claims against the Company.

Article 8TERM AND TERMINATION.

The term of this Agreement shall begin on the Effective Date and shall end upon the earlier of:

(a)The date on which the Company ceases to exist under this Agreement or under other applicable law; and

(b)The date on which the Parties determine to terminate the Agreement.

Article 9MISCELLANEOUS PROVISIONS.

9.1ENTIRE AGREEMENT.

This Agreement contains the complete agreement between the parties concerning its subject matter, and it replaces all earlier agreements between them, whether written or oral, concerning its subject matter.

9.2AMENDMENTS.

No amendment of this Agreement or of the Certificate shall be valid unless it is set forth in a writing signed by both parties.

9.3NOTICES.

All notices under this Agreement shall be in writing.  They shall be sent by fax or by registered U.S. mail, return receipt requested, to the parties at their respective addresses as stated below:

If to the Company:	New Millennium Building Systems, LLC 6714 Point Inverness Way, Suite 200 Fort Wayne, IN  46804 Fax:  260-969-3592
If to the Member:	Steel Dynamics, Inc. 6714 Point Inverness Way, Suite 200 Fort Wayne, IN  46804 Fax:  260-969-3592

A party may change the party’s address for purposes of this Article 9.3 at any time upon reasonable notice to the other parties.  Notices shall be deemed to have been received when actually received.

9.4GOVERNING LAW.

This Agreement shall be governed exclusively by the laws of the State of Indiana (exclusive of its laws relating to conflicts of law).

9.5CAPTIONS.

Captions in this Agreement are for convenience only and shall be deemed irrelevant in construing its provisions.

9.6INCORPORATION OF ARTICLES, ETC.

The Articles and all exhibits referred to in this Agreement are hereby incorporated in the Agreement and made an integral part of it.

9.7DEFINITION OF “INCLUDING,” “PERSON,” ETC.

The terms “including” and “includes” shall mean a partial definition.  The term “person” shall mean a natural person and any kind of entity.

IN WITNESS of their acceptance of the above terms and conditions, the parties by themselves or by their duly authorized representatives have signed and dated this Agreement as follows:

“Member”	STEEL DYNAMICS, INC.
Dated: 4/10/06
	By:	/s/ Gary E. Heasley.
		Gary E. Heasley, Vice President and CFO
“Company”	NEW MILLENNIUM BUILDING SYSTEMS, LLC
Dated: 4/10/06
	By:	/s/ Bert D. Hollman.
		Bert D. Hollman, President

EXHIBIT “A”

Capital Contributions and Membership Interests of Members

Member	Capital Contribution	Membership Interests
Steel Dynamics, Inc.	$	100	%