| Henry's Metal Polishing, Inc Turning, Bending, Welding, Grinding, Finishing · ISO 9001 | S El Monte, CA | TurningBendingWeldingGrindingFinishing | ISO 9001 |
| Hi Performance Machine & Metals, Inc Milling, Turning, Waterjet, EDM · ISO 9001 | Lakeside, CA | MillingTurningWaterjetEDM | ISO 9001 |
| High Speed CNC Milling, Turning · ISO 9001, AS9100 | Santa Clara, CA | MillingTurning | ISO 9001, AS9100 |
| Hilltop Technology Laboratory Inc Milling | Irvine, CA | Milling | - |
| HM Quality Machining Inc Milling, Turning, Laser, Waterjet, Grinding | Ontario, CA | MillingTurningLaserWaterjetGrinding | - |
| HMF Corporation Bending, Laser, Welding | Anaheim, CA | BendingLaserWelding | - |
| HNDO Precision Milling, Laser, Finishing | Santa Rosa, CA | MillingLaserFinishing | - |
| HP Machine & Engineering Inc Milling, Turning, EDM | San Jose, CA | MillingTurningEDM | - |
| HPR Machine Milling, Turning | Vista, CA | MillingTurning | - |
| Hubbell Machine Co Inc Milling, Turning, Finishing · ISO 9001, AS9100 | Paso Robles, CA | MillingTurningFinishing | ISO 9001, AS9100 |
| Hunt Enterprises Milling, Turning, Welding | Santa Ana, CA | MillingTurningWelding | - |
| Hyperformance Products Inc Milling, Turning, Punching, Bending, Welding | Huntington Beach, CA | MillingTurningPunchingBendingWelding | - |
| Infiniti Manufacture Milling, Welding, Finishing | Corona, CA | MillingWeldingFinishing | - |
| Infinity Precision Inc Milling, Turning, Waterjet, Bending, Grinding · ISO 9001, AS9100 | Simi Valley, CA | MillingTurningWaterjetBendingGrinding | ISO 9001, AS9100 |
| Infocus CNC Machining, Inc Milling, Turning, Swiss · ISO 9001, AS9100 | Fountain Valley, CA | MillingTurningSwiss | ISO 9001, AS9100 |
| Innovation Alley Milling, Turning, Bending, Welding | Fresno, CA | MillingTurningBendingWelding | - |
| Inspirnetics, Inc Milling, Turning | Rancho Cucamonga, CA | MillingTurning | - |
| Inventery Precision Milling, Turning, Swiss, Finishing, Assembly · ISO 9001, AS9100, ITAR, CMMC | Pasadena, CA | MillingTurningSwissFinishingAssembly | ISO 9001, AS9100, ITAR, CMMC |
| J A-Co Machine Works, LLC Milling, Turning, Swiss, Welding, Finishing, Assembly · ISO 9001, AS9100, ITAR, NADCAP, ISO 13485 | Scotts Valley, CA | MillingTurningSwissWeldingFinishingAssembly | ISO 9001, AS9100, ITAR, NADCAP, ISO 13485 |
| J. I. Machine Co., Inc Milling, Turning, Swiss · ISO 9001, AS9100, ITAR | San Diego, CA | MillingTurningSwiss | ISO 9001, AS9100, ITAR |
| Jaco Engineering Milling, Turning, Bending, Welding, EDM, Grinding, Finishing, Assembly · NADCAP | Anaheim, CA | MillingTurningBendingWeldingEDMGrindingFinishingAssembly | NADCAP |
| Jaffa Precision Engineering Inc Milling, Turning, Swiss, Welding, Grinding, Finishing · ISO 9001 | Riverside, CA | MillingTurningSwissWeldingGrindingFinishing | ISO 9001 |
| Jars Inc Milling, Waterjet, Bending, Welding, EDM, Grinding, Finishing | San Fernando, CA | MillingWaterjetBendingWeldingEDMGrindingFinishing | - |
| Jarvis Manufacturing, Inc Milling, Turning, EDM, Assembly · ISO 9001, ITAR | San Jose, CA | MillingTurningEDMAssembly | ISO 9001, ITAR |
| Jerry's Welding & Machine Welding | San Diego, CA | Welding | - |
| Joels Machine Shop Inc Milling, Turning, Grinding | El Monte, CA | MillingTurningGrinding | - |
| Johnson Manufacturing Milling, Turning, Grinding · AS9100 | Huntington Beach, CA | MillingTurningGrinding | AS9100 |
| JP Metal Fabrication, Inc. Milling, Bending, Laser, Welding | Santa Clara, CA | MillingBendingLaserWelding | - |
| JWP Manufacturing Milling, Swiss, EDM | Santa Clara, CA | MillingSwissEDM | - |
| Kaydek Machining, Inc Milling, Turning, Finishing · ISO 9001, AS9100 | San Jose, CA | MillingTurningFinishing | ISO 9001, AS9100 |
| KD Precision Machining Inc Milling, Turning · AS9100 | Corona, CA | MillingTurning | AS9100 |
| King Tek EDM & Precision Machining Milling, Bending, Welding, EDM · ISO 9001, AS9100, ITAR, NADCAP | Anaheim, CA | MillingBendingWeldingEDM | ISO 9001, AS9100, ITAR, NADCAP |
| KNM Manufacturing Inc Bending | Fremont, CA | Bending | - |
| L.F. Industries, Inc Milling · ISO 9001, AS9100 | Carlsbad, CA | Milling | ISO 9001, AS9100 |
| L&B Labs Milling, Turning, Laser, Welding, EDM, Grinding | San Jose, CA | MillingTurningLaserWeldingEDMGrinding | - |
| La Gauge Co Milling, Turning, EDM, Grinding, Finishing · ISO 9001, AS9100, ITAR | Sun Valley, CA | MillingTurningEDMGrindingFinishing | ISO 9001, AS9100, ITAR |
| Laserbend, LLC Laser, Bending, Welding, Finishing | Tujunga, CA | LaserBendingWeldingFinishing | - |
| Laserworx Mfg Laser, Bending, Welding, Stamping · AS9100, ITAR | Oxnard, CA | LaserBendingWeldingStamping | AS9100, ITAR |
| Lightsout CNC Manufacturing Company Milling · ISO 9001, ITAR, NADCAP, ISO 13485, CMMC | Beverly Hills, CA | Milling | ISO 9001, ITAR, NADCAP, ISO 13485, CMMC |
| LNP Machining Milling, Turning, Welding, Finishing · ISO 9001, AS9100, ITAR, ISO 13485 | San Jose, CA | MillingTurningWeldingFinishing | ISO 9001, AS9100, ITAR, ISO 13485 |
| Long Machine Milling, Turning, Grinding | Temecula, CA | MillingTurningGrinding | - |
| Loutech LLC Milling, Turning, Swiss, Finishing · ISO 9001, AS9100, ITAR | Chino, CA | MillingTurningSwissFinishing | ISO 9001, AS9100, ITAR |
| LP Precision, Inc Milling, Turning, Grinding, Finishing | Santa Clara, CA | MillingTurningGrindingFinishing | - |
| LT CNC Machining Inc. Milling, Turning, Welding · AS9100 | San Diego, CA | MillingTurningWelding | AS9100 |
| Ltmt Machining LLC Milling, Finishing | Santa Clara, CA | MillingFinishing | - |
| Luna's Sheet Metal Inc Milling, Turning, Bending, Laser, Welding | Santa Clara, CA | MillingTurningBendingLaserWelding | - |
| M & R Engineering Milling, Turning, Swiss, Finishing, Assembly · ISO 9001, AS9100, ITAR, NADCAP | Orange, CA | MillingTurningSwissFinishingAssembly | ISO 9001, AS9100, ITAR, NADCAP |
| M&M Machining, Inc Milling, Turning, Welding, Finishing | Ventura, CA | MillingTurningWeldingFinishing | - |
| Machina Labs Inc Stamping · ITAR, CMMC | Chatsworth, CA | Stamping | ITAR, CMMC |
| Machineworks Manufacturing Milling, Turning, Laser, Bending, Welding, Finishing · ISO 9001, AS9100, ITAR | Northridge, CA | MillingTurningLaserBendingWeldingFinishing | ISO 9001, AS9100, ITAR |