| Lima Sheet Metal Machine and Mfg., Inc Turning, Bending, Welding, Grinding | Lima, OH | TurningBendingWeldingGrinding | - |
| Limestone Manufacturing LLC Milling, Turning, Laser, Bending, Welding, Metal AM, EDM, Grinding · ISO 9001, AS9100 | Somerset, KY | MillingTurningLaserBendingWeldingMetal AMEDMGrinding | ISO 9001, AS9100 |
| Lindsay Machine Works, Inc Milling, Turning, Laser, Waterjet, Bending, Welding, Grinding | Independence, MO | MillingTurningLaserWaterjetBendingWeldingGrinding | - |
| Logan Machine Co Milling, Turning, Bending, Welding | Akron, OH | MillingTurningBendingWelding | - |
| M & M Sheet Metal, Inc Milling, Laser, Bending, Welding, Forging · ISO 9001, ITAR, CMMC | Williamsport, PA | MillingLaserBendingWeldingForging | ISO 9001, ITAR, CMMC |
| M & S Machining Inc Milling, Turning, Bending, Welding, EDM, Assembly · ISO 9001, AS9100, ITAR | Winchester, KY | MillingTurningBendingWeldingEDMAssembly | ISO 9001, AS9100, ITAR |
| M.a. Metal Co., Inc Laser, Bending, Welding, Stamping, Assembly · ISO 9001 | Columbus, IN | LaserBendingWeldingStampingAssembly | ISO 9001 |
| M&M Full Service Machine Shop Milling, Bending, Welding, Grinding, Finishing | Satellite Beach, FL | MillingBendingWeldingGrindingFinishing | - |
| M&M Metals Inc. Bending, Laser, Welding | San Antonio, TX | BendingLaserWelding | - |
| Mac Products, Inc Milling, Waterjet, Bending, Welding, Assembly · ISO 9001 | Kearny, NJ | MillingWaterjetBendingWeldingAssembly | ISO 9001 |
| Mac Smith Corp Milling, Turning, Laser, Waterjet, Bending, Welding, Stamping, Grinding | Gardena, CA | MillingTurningLaserWaterjetBendingWeldingStampingGrinding | - |
| Mac-Tech Turning, Bending, Laser, Welding | Milwaukee, WI | TurningBendingLaserWelding | - |
| Manor Tool & Manufacturing Co Milling, Laser, Waterjet, Bending, Welding, Stamping, EDM, Grinding, Finishing · ISO 9001, ITAR | Schiller Park, IL | MillingLaserWaterjetBendingWeldingStampingEDMGrindingFinishing | ISO 9001, ITAR |
| Maria Custom Sheet Metal Bending, Welding | Englewood, CO | BendingWelding | - |
| Mark One Metal Works Turning, Bending, Welding | Sparks, NV | TurningBendingWelding | - |
| Massie Mfg Inc Milling, Turning, Laser, Waterjet, Bending, Welding, Finishing · ITAR | Baraga, MI | MillingTurningLaserWaterjetBendingWeldingFinishing | ITAR |
| Master Metal Products Co Bending, Welding | San Jose, CA | BendingWelding | - |
| Master Tool & Manufacturing Inc Turning, Bending, Welding, EDM, Grinding · ISO 9001, ITAR | Hiawatha, IA | TurningBendingWeldingEDMGrinding | ISO 9001, ITAR |
| Matern Metal Works, Inc Punching, Bending, Welding | Mansfield, OH | PunchingBendingWelding | - |
| Max Machining LLC Milling, Turning, Laser, Bending · ITAR, CMMC | Telford, PA | MillingTurningLaserBending | ITAR, CMMC |
| McAlpin Industries Inc. Milling, Bending, Laser, Welding, Stamping | Rochester, NY | MillingBendingLaserWeldingStamping | - |
| McKenna Metal Bending, Laser, Welding, Waterjet | Portland, OR | BendingLaserWeldingWaterjet | - |
| McKiney Manufacturing Milling, Turning, Laser, Waterjet, Bending, Welding | Mitchell, NE | MillingTurningLaserWaterjetBendingWelding | - |
| MCW Certified Welding Ltd Punching, Bending, Welding | Delta, OH | PunchingBendingWelding | - |
| Megla Manufacturing, Inc. Milling, Bending, Laser, Welding, Waterjet | National City, CA | MillingBendingLaserWeldingWaterjet | - |
| Melting Point Metalworks LLC Laser, Bending, Welding | Brownsburg, IN | LaserBendingWelding | - |
| Metal Masterminds Laser, Waterjet, Punching, Bending, Welding, Stamping | Fountain Valley, CA | LaserWaterjetPunchingBendingWeldingStamping | - |
| Metal Pro, Inc. Milling, Bending, Welding | Phoenix, AZ | MillingBendingWelding | - |
| Metal Workz L.L.C Milling, Turning, Laser, Bending, Welding, Finishing | Albany, KY | MillingTurningLaserBendingWeldingFinishing | - |
| Metalcraft Creative Bending, Laser, Welding | Birmingham, AL | BendingLaserWelding | - |
| Metalcraft Inc Bending, Laser, Welding | Boise, ID | BendingLaserWelding | - |
| Metalcraft Services Of Tampa, LLC. Bending, Welding, Waterjet, Stamping | Tampa, FL | BendingWeldingWaterjetStamping | - |
| MetalMania Bending, Laser, Welding | Brooklyn, NY | BendingLaserWelding | - |
| Metalmasters Milling, Turning, Bending, Welding, Finishing | Brighton, CO | MillingTurningBendingWeldingFinishing | - |
| Metco Metal Fab. Bending, Laser, Welding | Chattanooga, TN | BendingLaserWelding | - |
| Metplas Inc Milling, Turning, Waterjet, Punching, Bending, Assembly · ISO 9001 | Natrona Heights, PA | MillingTurningWaterjetPunchingBendingAssembly | ISO 9001 |
| Microform Precision LLC Turning, Bending, Laser, Welding, Waterjet | Sacramento, CA | TurningBendingLaserWeldingWaterjet | - |
| Mid-State Metals Bending, Welding | Orlando, FL | BendingWelding | - |
| Midlake Products & Mfg. Co., Inc Turning, Bending, Laser, Welding, Stamping | Canton, OH | TurningBendingLaserWeldingStamping | - |
| Midwest Precision Inc Bending, Laser, Welding, Waterjet · ISO 9001 | Tulsa, OK | BendingLaserWeldingWaterjet | ISO 9001 |
| 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 |
| Millennium Metalcraft, Inc Milling, Laser, Bending, Welding, Finishing, Assembly · ISO 9001 | Fremont, CA | MillingLaserBendingWeldingFinishingAssembly | ISO 9001 |
| Millwood Metalworks Punching, Bending, Welding | Freeport, MN | PunchingBendingWelding | - |
| Milwaukee Metal Products Co Bending, Welding, Stamping | Milwaukee, WI | BendingWeldingStamping | - |
| Mission Critical Solutions LLC Milling, Punching, Bending, Welding | Alum Bank, PA | MillingPunchingBendingWelding | - |
| MJM Manufacturing Inc Milling, Laser, Punching, Bending, Welding, Stamping · ISO 9001, AS9100, ITAR | Miami Lakes, FL | MillingLaserPunchingBendingWeldingStamping | ISO 9001, AS9100, ITAR |
| MM Industries Tech LLC Laser, Punching, Bending, Welding, Assembly | Stanwood, WA | LaserPunchingBendingWeldingAssembly | - |
| Mofab Inc Milling, Laser, Waterjet, Bending, Welding | Anderson, IN | MillingLaserWaterjetBendingWelding | - |
| Motion Metalworks LLC Laser, Waterjet, Bending, Welding, Finishing | Wrens, GA | LaserWaterjetBendingWeldingFinishing | - |