SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person* HEARTLAND INDUSTRIAL ASSOCIATES LLC (Last) (First) (Middle) 55 RAILROAD AVENUE 3RD FLOOR (Street) GREENWICH CT 06830 (City) (State) (Zip)	2. Date of Event Requiring Statement (Month/Day/Year) 05/17/2007	3. Issuer Name and Ticker or Trading Symbol TRIMAS CORP [ TRS ]
		4. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director X 10% Owner Officer (give title below) Other (specify below)	5. If Amendment, Date of Original Filed (Month/Day/Year)
			6. Individual or Joint/Group Filing (Check Applicable Line) Form filed by One Reporting Person X Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock	11,805,779(1)(6)	D
Common Stock	2,243,827(2)(6)	D
Common Stock	835,339(3)(6)	D
Common Stock	173,378(4)(6)	D
Common Stock	32,952(5)(6)	D

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

1. Name and Address of Reporting Person* HEARTLAND INDUSTRIAL ASSOCIATES LLC (Last) (First) (Middle) 55 RAILROAD AVENUE 3RD FLOOR (Street) GREENWICH CT 06830 (City) (State) (Zip)

1. Name and Address of Reporting Person* TriMas Investment Fund I, LLC (Last) (First) (Middle) 55 RAILROAD AVENUE 3RD FLOOR (Street) GREENWICH CT 06830 (City) (State) (Zip)

1. Name and Address of Reporting Person* Metaldyne Investment Fund I, LLC (Last) (First) (Middle) 55 RAILROAD AVENUE 3RD FLOOR (Street) GREENWICH CT 06830 (City) (State) (Zip)

1. Name and Address of Reporting Person* Metaldyne Investment Fund II, LLC (Last) (First) (Middle) 55 RAILROAD AVENUE 3RD FLOOR (Street) GREENWICH CT 06830 (City) (State) (Zip)

1. Name and Address of Reporting Person* HIP Side-by-Side Partners, LP (Last) (First) (Middle) 55 RAILROAD AVENUE 3RD FLOOR (Street) GREENWICH CT 06830 (City) (State) (Zip)

1. Name and Address of Reporting Person* TriMas Investment Fund II, LLC (Last) (First) (Middle) 55 RAILROAD AVENUE 3RD FLOOR (Street) GREENWICH CT 06830 (City) (State) (Zip)

Explanation of Responses:

1. These securities are owned directly by TriMas Investment Fund I, L.L.C. (?TriMas I?). Heartland Industrial Associates, L.L.C. (?Heartland?), the Managing Member of TriMas I, is an indirect beneficial owner of these securities.

2. These securities are owned directly by Metaldyne Investment Fund I, L.L.C. (?Metaldyne I?). Heartland, the Managing Member of Metaldyne I, is an indirect beneficial owner of these securities.

3. These securities are owned directly by HIP Side-by-Side Partners, L.P. (?HIP?). Heartland, the General Partner of HIP, is an indirect beneficial owner of these securities.

4. These securities are owned directly by TriMas Investment Fund II, L.L.C. (?TriMas II?). Heartland, the Managing Member of TriMas II, is an indirect beneficial owner of these securities.

5. These securities are owned directly by Metaldyne Investment Fund II, L.L.C. (?Metaldyne II?). Heartland, the Managing Member of Metaldyne II, is an indirect beneficial owner of these securities.

6. Heartland, TriMas I, Metaldyne I, HIP, TriMas II and Metaldyne II may be deemed to be members of a ?group? for purposes of Section 13(d) of the Securities Exchange Act of 1934 (the ?Exchange Act?). By reason of TriMas Corporation?s (the ?Company?) shareholders agreement (the ?Shareholders Agreement?), dated as of June 6, 2002, as amended, holders of an additional 5,534,756 shares of the Company?s common stock have entered into certain voting agreements with affiliates of Heartland.

Remarks:

	Heartland Industrial Associates, L.L.C. /s/ Daniel P. Tredwell, Managing Member	05/17/2007
	TriMas Investment Fund I, L.L.C., By: Heartland Industrial Associates, L.L.C., its Managing Member, /s/ Daniel P. Tredwell, Managing Member	05/17/2007
	TriMas Investment Fund II, L.L.C., By: Heartland Industrial Associates, L.L.C., its Managing Member, /s/ Daniel P. Tredwell, Managing Member	05/17/2007
	Metaldyne Investment Fund I, L.L.C., By: Heartland Industrial Associates, L.L.C., its Managing Member, /s/ Daniel P. Tredwell, Managing Member	05/17/2007
	Metaldyne Investment Fund II, L.L.C., By: Heartland Industrial Associates, L.L.C., its Managing Member, /s/ Daniel P. Tredwell, Managing Member	05/17/2007
	HIP Side-by-Side Partners, L.P., By: Heartland Industrial Associates, L.L.C., its Managing Member, /s/ Daniel P. Tredwell, Managing Member	05/17/2007
	** Signature of Reporting Person	Date
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