| Liberty Precision Company Milling, Turning, EDM, Grinding, Assembly · ISO 9001 | Houston, TX | MillingTurningEDMGrindingAssembly | ISO 9001 |
| Lindquist Machine Co., LLC Welding · ISO 9001 | Green Bay, WI | Welding | ISO 9001 |
| Logan Machine Co Milling, Turning, Bending, Welding | Akron, OH | MillingTurningBendingWelding | - |
| Long Machine Milling, Turning, Grinding | Temecula, CA | MillingTurningGrinding | - |
| Loper Machine LLC Milling, Turning | Edgewood, MD | MillingTurning | - |
| LP Precision, Inc Milling, Turning, Grinding, Finishing | Santa Clara, CA | MillingTurningGrindingFinishing | - |
| Luso Machine NJ, LLC Milling, Turning, Welding, EDM · ISO 9001 | Newark, NJ | MillingTurningWeldingEDM | ISO 9001 |
| M & M Sheet Metal, Inc Milling, Laser, Bending, Welding, Forging · ISO 9001, ITAR, CMMC | Williamsport, PA | MillingLaserBendingWeldingForging | ISO 9001, ITAR, CMMC |
| M 7 Technologies Bending, Welding · ISO 9001 | Youngstown, OH | BendingWelding | ISO 9001 |
| M W M Services, Inc Milling, Welding, EDM | Riviera Beach, FL | MillingWeldingEDM | - |
| M-Tech Machining LLC Milling, Turning, EDM · ITAR | Edgewood, NM | MillingTurningEDM | ITAR |
| Mac Smith Corp Milling, Turning, Laser, Waterjet, Bending, Welding, Stamping, Grinding | Gardena, CA | MillingTurningLaserWaterjetBendingWeldingStampingGrinding | - |
| Mach Nine LLC Welding | Houston, TX | Welding | - |
| Machina Labs Inc Stamping · ITAR, CMMC | Chatsworth, CA | Stamping | ITAR, CMMC |
| Machine Craft Northwest Inc Milling, Turning, Welding | Lebanon, OR | MillingTurningWelding | - |
| Machine Shop LLC EDM, Assembly | East Hardwick, VT | EDMAssembly | - |
| Machine Tech Inc Milling, Turning, EDM · ISO 9001 | Houma, LA | MillingTurningEDM | ISO 9001 |
| Machine Time Inc Milling, Turning, Bending, Welding · ISO 9001, AS9100 | Nicholasville, KY | MillingTurningBendingWelding | ISO 9001, AS9100 |
| Machine Tool Services Turning, Bending, EDM | Spokane, WA | TurningBendingEDM | - |
| Machinewell, Inc Milling, Welding · ISO 9001 | Grygla, MN | MillingWelding | ISO 9001 |
| Machinist Group Corporation Milling, Turning, Waterjet · ISO 9001, ITAR | Reno, NV | MillingTurningWaterjet | ISO 9001, ITAR |
| Magna Tool Inc Milling, Turning, Welding · AS9100 | Cypress, CA | MillingTurningWelding | AS9100 |
| Magnetic Inspection Laboratory, Inc Milling, Welding, Finishing · ISO 9001, AS9100, NADCAP, ISO 13485 | Elk Grove Village, IL | MillingWeldingFinishing | ISO 9001, AS9100, NADCAP, ISO 13485 |
| Malux Machine LLC Milling, Turning, Welding, Grinding | Stratford, CT | MillingTurningWeldingGrinding | - |
| Manufacturing Standard, LLC Milling, Turning, Swiss, Stamping, Casting · ISO 9001, AS9100, IATF 16949 | Poway, CA | MillingTurningSwissStampingCasting | ISO 9001, AS9100, IATF 16949 |
| Marcu Manufacturing of Georgia, LLC Milling, Turning, Stamping · ISO 9001 | Buford, GA | MillingTurningStamping | ISO 9001 |
| Marsam Metal Finishing Co Finishing, Assembly | New Britain, CT | FinishingAssembly | - |
| Marton Precision MF Milling, Turning, Waterjet, Welding, EDM, Finishing · ISO 9001, AS9100, ITAR | Fullerton, CA | MillingTurningWaterjetWeldingEDMFinishing | ISO 9001, AS9100, ITAR |
| Masters Machine Company Milling, Turning, Swiss, Grinding, Finishing · ISO 9001, ITAR | Bristol, ME | MillingTurningSwissGrindingFinishing | ISO 9001, ITAR |
| Matern Metal Works, Inc Punching, Bending, Welding | Mansfield, OH | PunchingBendingWelding | - |
| Matrix Metalworks LLC Milling, Welding · ISO 9001 | Sugar Land, TX | MillingWelding | ISO 9001 |
| Max Machining LLC Milling, Turning, Laser, Bending · ITAR, CMMC | Telford, PA | MillingTurningLaserBending | ITAR, CMMC |
| MaxFab Milling, Laser, Punching, Bending, Welding, Stamping, Finishing, Assembly | Madison, AL | MillingLaserPunchingBendingWeldingStampingFinishingAssembly | - |
| Maxpol Precision Machining Milling, Turning | Morgan Hill, CA | MillingTurning | - |
| Maxsteel Fabrication, LLC Milling, Turning, Laser, Welding, Finishing | Paris, TN | MillingTurningLaserWeldingFinishing | - |
| MBK Machine Corp Milling, Turning, Laser, EDM, Grinding · ITAR | Mead, CO | MillingTurningLaserEDMGrinding | ITAR |
| McAllister Tool & Machine Inc Milling, Turning, Swiss · ISO 9001, AS9100, ITAR | Huntsville, AL | MillingTurningSwiss | ISO 9001, AS9100, ITAR |
| McKenna Metal Bending, Laser, Welding, Waterjet | Portland, OR | BendingLaserWeldingWaterjet | - |
| McKenzie Machining Inc Milling, Turning, EDM, Grinding · ISO 9001, AS9100, ITAR | San Jose, CA | MillingTurningEDMGrinding | ISO 9001, AS9100, ITAR |
| Mecha Inc Milling, Bending, Welding, Waterjet · ISO 9001, ITAR, NADCAP | Raleigh, NC | MillingBendingWeldingWaterjet | ISO 9001, ITAR, NADCAP |
| Medical Micro Machining Inc Milling | Colfax, WA | Milling | - |
| Mercury Aircraft Inc Milling, Laser, Punching, Bending, Welding, Stamping, Assembly · ISO 9001, AS9100, ITAR | Hammondsport, NY | MillingLaserPunchingBendingWeldingStampingAssembly | ISO 9001, AS9100, ITAR |
| Meridian Industrial Group, LLC Milling, Turning, Welding, Casting · ISO 9001, AS9100 | Holyoke, MA | MillingTurningWeldingCasting | ISO 9001, AS9100 |
| Meridian Manufacturing Inc Milling, Turning, Laser, Welding, EDM, Grinding, Finishing | Ballston Spa, NY | MillingTurningLaserWeldingEDMGrindingFinishing | - |
| Mesco Manufacturing Group LLC Milling, Laser, Welding, Finishing · ISO 9001 | Greensburg, IN | MillingLaserWeldingFinishing | ISO 9001 |
| Met International Trading Company, Inc Laser, Punching, Bending, Welding, Finishing | Houston, TX | LaserPunchingBendingWeldingFinishing | - |
| Metal Components LLC Turning, Waterjet, Bending, Welding, Finishing, Assembly · ISO 9001 | Grand Rapids, MI | TurningWaterjetBendingWeldingFinishingAssembly | ISO 9001 |
| Metal Fabricators Plus LLC Laser, Waterjet, Bending, Welding | Indianapolis, IN | LaserWaterjetBendingWelding | - |
| Metal Man Milling, Waterjet, Bending, Welding | Watertown, NY | MillingWaterjetBendingWelding | - |
| Metaltech Inc Laser, Bending, Welding, Assembly · AS9100 | Auburn, WA | LaserBendingWeldingAssembly | AS9100 |