| McAlpin Industries Inc. Milling, Bending, Laser, Welding, Stamping | Rochester, NY | MillingBendingLaserWeldingStamping | - |
| McClintic R-D-M, Inc Milling, Turning, Waterjet, Welding | Albuquerque, NM | MillingTurningWaterjetWelding | - |
| McCormick Industries Inc Milling, Turning, Swiss, Welding, Grinding, Finishing, Assembly · ISO 9001 | Appleton, WI | MillingTurningSwissWeldingGrindingFinishingAssembly | ISO 9001 |
| McGinley Manufacturing Milling, Turning, Swiss, Welding, EDM · ISO 13485 | Glenrock, WY | MillingTurningSwissWeldingEDM | ISO 13485 |
| McKenna Metal Bending, Laser, Welding, Waterjet | Portland, OR | BendingLaserWeldingWaterjet | - |
| McKiney Manufacturing Milling, Turning, Laser, Waterjet, Bending, Welding | Mitchell, NE | MillingTurningLaserWaterjetBendingWelding | - |
| McNeil Industries Inc Milling, Turning, Welding, Stamping, Grinding, Assembly · ISO 9001, AS9100 | Painesville, OH | MillingTurningWeldingStampingGrindingAssembly | ISO 9001, AS9100 |
| MCW Certified Welding Ltd Punching, Bending, Welding | Delta, OH | PunchingBendingWelding | - |
| Mdi Manufacturing Inc Milling, Turning, Welding, Grinding, Assembly · ISO 9001 | Lakewood, NJ | MillingTurningWeldingGrindingAssembly | ISO 9001 |
| Mecca Design & Production Welding | Dallas, TX | Welding | - |
| Mechanical Development Company, Incorporated Welding | Salem, VA | Welding | - |
| Mega Machine Shop Inc Milling, Turning, Welding | Tumwater, WA | MillingTurningWelding | - |
| Melton Sheet Metal Bending, Welding | Fresno, CA | BendingWelding | - |
| Memac Industries Inc Milling, Turning, Welding, Grinding | Lancaster, OH | MillingTurningWeldingGrinding | - |
| Menco LLC Welding, Assembly | Wallace, MI | WeldingAssembly | - |
| Mennie's Machine Co Milling, Turning, Welding, Grinding · IATF 16949 | Mark, IL | MillingTurningWeldingGrinding | IATF 16949 |
| Menze Precision Machining, LLC Milling, Turning, Bending, Welding, EDM, Grinding, Finishing | Winter Haven, FL | MillingTurningBendingWeldingEDMGrindingFinishing | - |
| Mercury Machining Co Milling, Turning, Welding, Grinding | Pensacola, FL | MillingTurningWeldingGrinding | - |
| 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 | - |
| Merritt Welding & Fabrication Bending, Welding | Denver, CO | BendingWelding | - |
| Met International Trading Company, Inc Laser, Punching, Bending, Welding, Finishing | Houston, TX | LaserPunchingBendingWeldingFinishing | - |
| Meta-Tech Industries, Inc Milling, Turning, Welding, EDM, Finishing · ISO 9001 | Houston, TX | MillingTurningWeldingEDMFinishing | ISO 9001 |
| Metal Fusion Inc Milling, Turning, Welding, Grinding | Redwood City, CA | MillingTurningWeldingGrinding | - |
| Metal Industries, Inc Milling, Turning, Welding | Hartford, CT | MillingTurningWelding | - |
| Metal Integrity, Inc Milling, Laser, Welding | Bellefonte, PA | MillingLaserWelding | - |
| Metal Man Milling, Waterjet, Bending, Welding | Watertown, NY | MillingWaterjetBendingWelding | - |
| Metal Master Inc Milling, Welding | San Diego, CA | MillingWelding | - |
| Metal Masterminds Laser, Waterjet, Punching, Bending, Welding, Stamping | Fountain Valley, CA | LaserWaterjetPunchingBendingWeldingStamping | - |
| Metal Pro, Inc. Milling, Bending, Welding | Phoenix, AZ | MillingBendingWelding | - |
| Metal Works Precision Machine and Tool, Inc Milling, Turning, Welding | Tucson, AZ | MillingTurningWelding | - |
| Metalcraft Industries, Inc Welding, Stamping, Finishing, Assembly · CMMC | Denver, CO | WeldingStampingFinishingAssembly | CMMC |
| Metalogic Industries LLC Milling, Turning, Swiss, Laser, Welding, EDM, Grinding | Southbridge, MA | MillingTurningSwissLaserWeldingEDMGrinding | - |
| MetalWork Austin Bending, Welding | Austin, TX | BendingWelding | - |
| Metalworking Group Bending, Welding · CMMC, ISO 9001, ITAR | Cincinnati, OH | BendingWelding | CMMC, ISO 9001, ITAR |
| Metzger Machine Co. Milling, Turning, Welding | Cincinnati, OH | MillingTurningWelding | - |
| Meyer Tool & Manufacturing, Inc Milling, Turning, Welding · ITAR | Oak Lawn, IL | MillingTurningWelding | ITAR |
| MFC Netform LLC Milling, Laser, Waterjet, Bending, Welding, Stamping, Forging, EDM, Grinding · ISO 9001, IATF 16949 | Shelby Township, MI | MillingLaserWaterjetBendingWeldingStampingForgingEDMGrinding | ISO 9001, IATF 16949 |
| Micar Fabrication Milling, Turning, Welding | Las Vegas, NV | MillingTurningWelding | - |
| Micro Machine & Electronics, Inc Milling, Turning, Welding, Grinding, Finishing, Assembly · ITAR | Leominster, MA | MillingTurningWeldingGrindingFinishingAssembly | ITAR |
| Micro Metals Inc Milling, Laser, Waterjet, Punching, Bending, Welding | Colorado Springs, CO | MillingLaserWaterjetPunchingBendingWelding | - |
| Mid-Continent Engineering, LLC Bending, Welding, Grinding, Finishing · ISO 9001, AS9100, ITAR | Minneapolis, MN | BendingWeldingGrindingFinishing | ISO 9001, AS9100, ITAR |
| Middletown Industrial Technologies, LLC Milling, Turning, Welding, Stamping, Assembly | Middletown, OH | MillingTurningWeldingStampingAssembly | - |
| Midwest Tool Inc Milling, Turning, Welding, EDM, Grinding | Joplin, MO | MillingTurningWeldingEDMGrinding | - |
| Midwest Tool Inc. Milling, Bending, Welding | Chicago, IL | MillingBendingWelding | - |
| Mikron Manufacturing Inc Milling, Turning, Laser, Punching, Bending, Welding, Finishing, Assembly · ISO 9001, ITAR | Colorado Springs, CO | MillingTurningLaserPunchingBendingWeldingFinishingAssembly | ISO 9001, ITAR |
| Miller CNC Milling, Turning, Welding, Grinding · ISO 9001, AS9100 | Chula Vista, CA | MillingTurningWeldingGrinding | ISO 9001, AS9100 |
| Miller Diversified Machining Milling, Turning, Welding · ISO 9001, ITAR | Minneapolis, MN | MillingTurningWelding | ISO 9001, ITAR |
| Mills Machine Works Inc Milling, Turning, Welding, Grinding | Lawrence, MA | MillingTurningWeldingGrinding | - |
| Milton Manufacturing, Inc Turning, Bending, Welding, Stamping, Assembly · ITAR | Detroit, MI | TurningBendingWeldingStampingAssembly | ITAR |