| Redwood Machine Works, Inc Waterjet, Welding · ISO 9001, AS9100 | Oakland, CA | WaterjetWelding | ISO 9001, AS9100 |
| Rincon Engineering Corporation Milling, Turning, Laser, Waterjet, Punching, Welding, Stamping, EDM, Finishing · ISO 9001, AS9100 | Carpinteria, CA | MillingTurningLaserWaterjetPunchingWeldingStampingEDMFinishing | ISO 9001, AS9100 |
| Rivtec LLC Laser, Bending, Welding, Assembly | Santa Ana, CA | LaserBendingWeldingAssembly | - |
| SDS Engineering Milling, Turning, Grinding · ISO 9001 | Sun Valley, CA | MillingTurningGrinding | ISO 9001 |
| Sheetmetal Engineering Inc Milling, Laser, Punching, Bending, Welding · ISO 9001, AS9100 | Simi Valley, CA | MillingLaserPunchingBendingWelding | ISO 9001, AS9100 |
| Silicon Precision Machining Inc Milling, Turning | Fremont, CA | MillingTurning | - |
| Slag Factory Milling, Laser, Welding | Oroville, CA | MillingLaserWelding | - |
| SOS Steel Co Inc Welding | Santa Clara, CA | Welding | - |
| Surfacemode, Inc Milling · ISO 9001, AS9100, ITAR | San Diego, CA | Milling | ISO 9001, AS9100, ITAR |
| Swiss Wire EDM Milling, Turning, Welding, EDM · ISO 9001, ITAR, NADCAP | Costa Mesa, CA | MillingTurningWeldingEDM | ISO 9001, ITAR, NADCAP |
| T & T Metals Milling, Laser, Punching, Bending, Welding, Finishing · ISO 9001 | Covina, CA | MillingLaserPunchingBendingWeldingFinishing | ISO 9001 |
| Tecma Milling, Turning, Welding, Waterjet, EDM, Stamping, Casting · ISO 9001, AS9100, ITAR, NADCAP | Sacramento, CA | MillingTurningWeldingWaterjetEDMStampingCasting | ISO 9001, AS9100, ITAR, NADCAP |
| Tobar Industries Milling, Turning, Bending, Welding | San Jose, CA | MillingTurningBendingWelding | - |
| Tri Precision Sheetmetal, Inc. Bending, Laser, Welding · ISO 9001, AS9100 | Anaheim, CA | BendingLaserWelding | ISO 9001, AS9100 |
| Trussworks International Inc Bending, Welding · ISO 9001 | Pomona, CA | BendingWelding | ISO 9001 |
| United Western Industries Inc. Milling, Bending, Laser, Welding, Stamping · IATF 16949 | Fresno, CA | MillingBendingLaserWeldingStamping | IATF 16949 |
| US Precision Sheet Metal, Inc Milling, Laser, Punching, Welding, Assembly | Riverside, CA | MillingLaserPunchingWeldingAssembly | - |
| Veco Technologies, Inc. Milling, Turning, Welding, EDM | Fresno, CA | MillingTurningWeldingEDM | - |
| Vista Industries, Inc Welding, Finishing | Palmdale, CA | WeldingFinishing | - |
| Weldtec Manufacturing, Inc Welding | Waterford, CA | Welding | - |
| Westcoast Precision, Inc Milling, Turning, Assembly · ISO 9001, AS9100, ITAR | San Jose, CA | MillingTurningAssembly | ISO 9001, AS9100, ITAR |
| Will-Mann Inc Turning, Laser, Punching, Bending, Welding · ISO 9001, AS9100 | Fullerton, CA | TurningLaserPunchingBendingWelding | ISO 9001, AS9100 |