| Ltmt Machining LLC Milling, Finishing | Santa Clara, CA | MillingFinishing | - |
| Luna's Sheet Metal Inc Milling, Turning, Bending, Laser, Welding | Santa Clara, CA | MillingTurningBendingLaserWelding | - |
| M & L Precision Machining, Inc EDM | Morgan Hill, CA | EDM | - |
| M & R Engineering Milling, Turning, Swiss, Finishing, Assembly · ISO 9001, AS9100, ITAR, NADCAP | Orange, CA | MillingTurningSwissFinishingAssembly | ISO 9001, AS9100, ITAR, NADCAP |
| Mac Cal Co Welding · ISO 13485 | San Jose, CA | Welding | ISO 13485 |
| Mac Smith Corp Milling, Turning, Laser, Waterjet, Bending, Welding, Stamping, Grinding | Gardena, CA | MillingTurningLaserWaterjetBendingWeldingStampingGrinding | - |
| Machina Labs Inc Stamping · ITAR, CMMC | Chatsworth, CA | Stamping | ITAR, CMMC |
| Machine Dimension, Inc Milling | San Jose, CA | Milling | - |
| Machinist Lab Milling, EDM | San Diego, CA | MillingEDM | - |
| Magna Tool Inc Milling, Turning, Welding · AS9100 | Cypress, CA | MillingTurningWelding | AS9100 |
| Manufacturing Standard, LLC Milling, Turning, Swiss, Stamping, Casting · ISO 9001, AS9100, IATF 16949 | Poway, CA | MillingTurningSwissStampingCasting | ISO 9001, AS9100, IATF 16949 |
| Mass Precision Inc Welding, Assembly · ISO 9001, ISO 13485 | San Jose, CA | WeldingAssembly | ISO 9001, ISO 13485 |
| Master Metal Products Co Bending, Welding | San Jose, CA | BendingWelding | - |
| Master Precision Machining Milling, Welding · ISO 9001, AS9100 | Santa Clara, CA | MillingWelding | ISO 9001, AS9100 |
| Maxpol Precision Machining Milling, Turning | Morgan Hill, CA | MillingTurning | - |
| McKenzie Machining Inc Milling, Turning, EDM, Grinding · ISO 9001, AS9100, ITAR | San Jose, CA | MillingTurningEDMGrinding | ISO 9001, AS9100, ITAR |
| Metal Fusion Inc Milling, Turning, Welding, Grinding | Redwood City, CA | MillingTurningWeldingGrinding | - |
| Metal Masterminds Laser, Waterjet, Punching, Bending, Welding, Stamping | Fountain Valley, CA | LaserWaterjetPunchingBendingWeldingStamping | - |
| Metalid Manufacturing Inc Milling · ISO 9001 | Pacoima, CA | Milling | ISO 9001 |
| Mgi/metalagraphics Milling, Turning | Moorpark, CA | MillingTurning | - |
| Microform Precision LLC Turning, Bending, Laser, Welding, Waterjet | Sacramento, CA | TurningBendingLaserWeldingWaterjet | - |
| Milco Wire EDM Inc Waterjet, Stamping, EDM · AS9100, ITAR, NADCAP | Huntington Beach, CA | WaterjetStampingEDM | AS9100, ITAR, NADCAP |
| Miller CNC Milling, Turning, Welding, Grinding · ISO 9001, AS9100 | Chula Vista, CA | MillingTurningWeldingGrinding | ISO 9001, AS9100 |
| Millipart, Inc Milling, Turning · ISO 9001, AS9100 | Glendora, CA | MillingTurning | ISO 9001, AS9100 |
| Milner's Anodizing Finishing · NADCAP | Santa Rosa, CA | Finishing | NADCAP |
| 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 |
| 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 |
| Neff Engineering LLC Milling, Laser, Welding | Los Angeles, CA | MillingLaserWelding | - |
| New World Machining Inc Milling, Turning, Welding | San Jose, CA | MillingTurningWelding | - |
| Next Intent, Inc Milling, Turning, Welding, EDM, Grinding, Assembly · ISO 9001, ITAR | San Luis Obispo, CA | MillingTurningWeldingEDMGrindingAssembly | ISO 9001, ITAR |
| Next Tech Manufacturing Inc Milling, Welding, Finishing | Santa Clara, CA | MillingWeldingFinishing | - |
| Nexus Automation Milling, Welding, EDM, Assembly · ISO 9001, ITAR, ISO 13485 | Livermore, CA | MillingWeldingEDMAssembly | ISO 9001, ITAR, ISO 13485 |
| Nocturnal Welding Welding | Camarillo, CA | Welding | - |
| Noron Precision Machining Inc Milling, Turning, Grinding, Finishing, Assembly · ISO 9001, ITAR | Sunnyvale, CA | MillingTurningGrindingFinishingAssembly | ISO 9001, ITAR |
| Norotos, Inc Turning, Forging | Santa Ana, CA | TurningForging | - |
| Omikron Engineering, Inc Milling, Turning, Swiss, Assembly · ISO 9001 | Chatsworth, CA | MillingTurningSwissAssembly | ISO 9001 |
| Opti-Forms Inc Stamping, EDM, Finishing · ISO 9001, ITAR | Temecula, CA | StampingEDMFinishing | ISO 9001, ITAR |
| Optima Precision Milling, Turning, Bending, Welding, EDM, Metal AM · ISO 9001, AS9100, ISO 13485, NADCAP | San Jose, CA | MillingTurningBendingWeldingEDMMetal AM | ISO 9001, AS9100, ISO 13485, NADCAP |
| Parallax Manufacturing LLC Milling, Turning, Bending, Welding, Stamping, Assembly · NADCAP | Lake Elsinore, CA | MillingTurningBendingWeldingStampingAssembly | NADCAP |
| PCL, LLC Milling, Turning, Swiss, Finishing · NADCAP | Oxnard, CA | MillingTurningSwissFinishing | NADCAP |
| Peacock Tool & Engineering Milling, Turning · AS9100, ITAR, CMMC | Spring Valley, CA | MillingTurning | AS9100, ITAR, CMMC |
| Pegasus Machining Solutions Milling, Turning, Finishing | San Jose, CA | MillingTurningFinishing | - |
| Perforated Panels Laser, Waterjet, Bending, Welding | Pacoima, CA | LaserWaterjetBendingWelding | - |
| Peridot Corp Laser, Welding | Pleasanton, CA | LaserWelding | - |
| 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 | - |
| Pimtad Aerospace LLC Milling, Turning, Swiss, Welding, Grinding, Assembly · AS9100 | Valencia, CA | MillingTurningSwissWeldingGrindingAssembly | AS9100 |