| Sintel Inc Laser, Punching, Bending, Welding, Finishing, Assembly | Spring Lake, MI | LaserPunchingBendingWeldingFinishingAssembly | - |
| Smith Brothers Tool Company Milling, Welding · ISO 9001, AS9100, ITAR | Shelby Township, MI | MillingWelding | ISO 9001, AS9100, ITAR |
| SpecWeld Milling, Welding, Assembly · ISO 9001 | Lake Orion, MI | MillingWeldingAssembly | ISO 9001 |
| Taylor Turning Inc Milling, Turning, Grinding | Wixom, MI | MillingTurningGrinding | - |
| Tel-X Corporation Milling, Turning, Laser, Welding, Stamping, EDM, Finishing · ISO 9001, IATF 16949 | Garden City, MI | MillingTurningLaserWeldingStampingEDMFinishing | ISO 9001, IATF 16949 |
| Tolerance Tool & Engineering Milling, Turning, Welding · ISO 9001, ITAR | Detroit, MI | MillingTurningWelding | ISO 9001, ITAR |
| Tri-County Precision Grinding Inc Milling, Grinding | Warren, MI | MillingGrinding | - |
| Trutron LLC Milling, Turning, EDM, Grinding | Troy, MI | MillingTurningEDMGrinding | - |
| U. P. Machine & Engineering Co Turning | Powers, MI | Turning | - |
| Unique Model Inc Milling, Turning, Welding, EDM, Grinding | Grand Rapids, MI | MillingTurningWeldingEDMGrinding | - |