| Manufacturing Standard, LLC Milling, Turning, Swiss, Stamping, Casting · ISO 9001, AS9100, IATF 16949 | Poway, CA | MillingTurningSwissStampingCasting | ISO 9001, AS9100, IATF 16949 |
| Mars Engineering Milling, Turning, Waterjet, EDM, Grinding, Finishing, Assembly | San Leandro, CA | MillingTurningWaterjetEDMGrindingFinishingAssembly | - |
| Martin's Metal Fabrication & Welding, Inc Milling, Turning, Laser, Waterjet, Bending, Welding | Vacaville, CA | MillingTurningLaserWaterjetBendingWelding | - |
| Marton Precision MF Milling, Turning, Waterjet, Welding, EDM, Finishing · ISO 9001, AS9100, ITAR | Fullerton, CA | MillingTurningWaterjetWeldingEDMFinishing | ISO 9001, AS9100, ITAR |
| Mass Precision Inc Welding, Assembly · ISO 9001, ISO 13485 | San Jose, CA | WeldingAssembly | ISO 9001, ISO 13485 |
| Master Precision Machining Milling, Welding · ISO 9001, AS9100 | Santa Clara, CA | MillingWelding | ISO 9001, AS9100 |
| McKenzie Machining Inc Milling, Turning, EDM, Grinding · ISO 9001, AS9100, ITAR | San Jose, CA | MillingTurningEDMGrinding | ISO 9001, AS9100, ITAR |
| Melton Sheet Metal Bending, Welding | Fresno, CA | BendingWelding | - |
| Metal Fusion Inc Milling, Turning, Welding, Grinding | Redwood City, CA | MillingTurningWeldingGrinding | - |
| Metal Master Inc Milling, Welding | San Diego, CA | MillingWelding | - |
| Metal Masterminds Laser, Waterjet, Punching, Bending, Welding, Stamping | Fountain Valley, CA | LaserWaterjetPunchingBendingWeldingStamping | - |
| Mikelson Machine Shop, Inc Milling, Turning | S El Monte, CA | MillingTurning | - |
| Miller CNC Milling, Turning, Welding, Grinding · ISO 9001, AS9100 | Chula Vista, CA | MillingTurningWeldingGrinding | ISO 9001, AS9100 |
| Millworx Precision Machining Inc Milling, Turning · ISO 9001, AS9100 | Corona, CA | MillingTurning | ISO 9001, AS9100 |
| Milo Engineering Milling, Turning, Grinding, Finishing · ISO 9001 | Torrance, CA | MillingTurningGrindingFinishing | ISO 9001 |
| Modus Advanced Milling, Waterjet, Finishing, Assembly · ISO 9001, AS9100, ITAR, CMMC | Carlsbad, CA | MillingWaterjetFinishingAssembly | ISO 9001, AS9100, ITAR, CMMC |
| Mono Engineering Corp Turning, Welding, EDM · ISO 9001 | Chatsworth, CA | TurningWeldingEDM | ISO 9001 |
| Morena Welding Inc Welding | San Diego, CA | Welding | - |
| MVN Machining LLC Milling, Turning | Santa Clara, CA | MillingTurning | - |
| My Machine Inc Milling · ISO 9001, AS9100, CMMC | Baldwin Park, CA | Milling | ISO 9001, AS9100, CMMC |
| O & Y Precision Inc Milling, Laser, Waterjet, Bending, Welding, EDM, Finishing, Assembly | Morgan Hill, CA | MillingLaserWaterjetBendingWeldingEDMFinishingAssembly | - |
| Odyssey Machining Milling, Finishing · ISO 9001, ITAR | San Jose, CA | MillingFinishing | ISO 9001, ITAR |
| Olson & Co. Steel Welding | Fresno, CA | Welding | - |
| Omanson Precision Engineering, Inc Milling, Finishing · ISO 9001, AS9100 | Chino, CA | MillingFinishing | ISO 9001, AS9100 |
| Omega Precision Milling, Turning · ISO 9001 | Santa Fe Springs, CA | MillingTurning | ISO 9001 |
| Omikron Engineering, Inc Milling, Turning, Swiss, Assembly · ISO 9001 | Chatsworth, CA | MillingTurningSwissAssembly | ISO 9001 |
| Orange County Sheet Metal Shop Bending, Laser, Welding, Stamping | Anaheim, CA | BendingLaserWeldingStamping | - |
| Pacon Mfg, Inc Milling, Turning, Welding, Finishing · ISO 9001 | Livermore, CA | MillingTurningWeldingFinishing | ISO 9001 |
| Pegasus Machining Solutions Milling, Turning, Finishing | San Jose, CA | MillingTurningFinishing | - |
| Perforated Panels Laser, Waterjet, Bending, Welding | Pacoima, CA | LaserWaterjetBendingWelding | - |
| Pervan Industries Milling, Turning, Waterjet, Punching, Bending · ISO 9001, AS9100 | Compton, CA | MillingTurningWaterjetPunchingBending | ISO 9001, AS9100 |
| Petersen Precision Engineering LLC Milling, Turning, Swiss, EDM, Grinding, Finishing · ISO 9001, AS9100, ISO 13485 | Redwood City, CA | MillingTurningSwissEDMGrindingFinishing | ISO 9001, AS9100, ISO 13485 |
| PHD Machining LLC Milling, EDM, Assembly | Santa Clara, CA | MillingEDMAssembly | - |
| PHES Machining Milling, Turning | Riverside, CA | MillingTurning | - |
| PL Machine Corporation Milling, Turning, Bending, Finishing · ISO 9001 | Los Alamitos, CA | MillingTurningBendingFinishing | ISO 9001 |
| Plasidyne Engineering & Manufacturing Milling, Turning · ISO 9001, AS9100, ITAR | Long Beach, CA | MillingTurning | ISO 9001, AS9100, ITAR |
| Pleasanton Tool & Manufacturing Inc Milling, Turning, Welding, EDM · ITAR | Pleasanton, CA | MillingTurningWeldingEDM | ITAR |
| PNM Co Milling, Turning · ISO 9001 | Fresno, CA | MillingTurning | ISO 9001 |
| Precision CNC Machining Milling, Turning · ISO 9001 | Oxnard, CA | MillingTurning | ISO 9001 |
| Precision Components Mfg Co Milling, Turning | Pasadena, CA | MillingTurning | - |
| Precision Machining & Fab Milling, Turning, Bending, Laser, Welding, Waterjet · ISO 9001, AS9100, ITAR | Anaheim, CA | MillingTurningBendingLaserWeldingWaterjet | ISO 9001, AS9100, ITAR |
| Precision Manufacturing Milling, Turning · ISO 9001, ITAR, ISO 13485 | Roseville, CA | MillingTurning | ISO 9001, ITAR, ISO 13485 |
| Process Stainless Lab Welding, Finishing, Assembly · ISO 9001 | Milpitas, CA | WeldingFinishingAssembly | ISO 9001 |
| Proformance Manufacturing Inc Turning, Stamping · ISO 9001 | Corona, CA | TurningStamping | ISO 9001 |
| Proto Solutions and Machining Turning, Welding, Assembly | San Diego, CA | TurningWeldingAssembly | - |
| Pulse Precision LLC Milling, EDM · ISO 9001 | Santa Ana, CA | MillingEDM | ISO 9001 |
| Q3-Cnc, Inc Milling, Turning | San Diego, CA | MillingTurning | - |
| Qualified Machine Shop Milling, Turning | San Diego, CA | MillingTurning | - |
| Quality Grinding Co, Inc Milling, Turning, Welding, Grinding, Finishing · ISO 9001, AS9100 | Buena Park, CA | MillingTurningWeldingGrindingFinishing | ISO 9001, AS9100 |
| Quantum Machining & Design Inc. Bending, Laser, Welding | Fresno, CA | BendingLaserWelding | - |