| John W. McDougall Co. Bending, Laser, Welding · ISO 9001 | Nashville, TN | BendingLaserWelding | ISO 9001 |
| JP Metal Fabrication, Inc. Milling, Bending, Laser, Welding | Santa Clara, CA | MillingBendingLaserWelding | - |
| K C Machine Milling, Turning, Waterjet · ISO 9001, AS9100 | Excelsior Springs, MO | MillingTurningWaterjet | ISO 9001, AS9100 |
| Kadon Precision Machining Turning · ISO 9001 | Rockford, IL | Turning | ISO 9001 |
| KCSP Machine LLC (formerly Kansas City Screw Products) Milling, Turning, Welding · ISO 9001, AS9100 | Kansas City, MO | MillingTurningWelding | ISO 9001, AS9100 |
| Kelley-Tron Machine Co Milling, Turning | Harrisburg, PA | MillingTurning | - |
| King Tek EDM & Precision Machining Milling, Bending, Welding, EDM · ISO 9001, AS9100, ITAR, NADCAP | Anaheim, CA | MillingBendingWeldingEDM | ISO 9001, AS9100, ITAR, NADCAP |
| Krukemeier Machine Milling, Turning, EDM · AS9100, NADCAP | Indianapolis, IN | MillingTurningEDM | AS9100, NADCAP |
| Kyron Tool & Machine Co., Inc Milling, Turning, Welding | Columbus, OH | MillingTurningWelding | - |
| L&M machining center Milling, Turning, Metal AM · AS9100, ITAR | Tucson, AZ | MillingTurningMetal AM | AS9100, ITAR |
| Lee Precision Machine Shop Inc. Milling, Turning, Bending, Welding, EDM · ISO 9001, ITAR | Athens, AL | MillingTurningBendingWeldingEDM | ISO 9001, ITAR |
| LJ Fabricators, Inc. Bending, Laser, Welding · ISO 9001 | Rockford, IL | BendingLaserWelding | ISO 9001 |
| LR Design+Build Laser, Welding, Metal AM | Columbus, OH | LaserWeldingMetal AM | - |
| LT CNC Machining Inc. Milling, Turning, Welding · AS9100 | San Diego, CA | MillingTurningWelding | AS9100 |
| Luna's Sheet Metal Inc Milling, Turning, Bending, Laser, Welding | Santa Clara, CA | MillingTurningBendingLaserWelding | - |
| Luso Machine NJ, LLC Milling, Turning, Welding, EDM · ISO 9001 | Newark, NJ | MillingTurningWeldingEDM | ISO 9001 |
| M & J Manufacturing, Inc. Milling, Turning, EDM | Portland, OR | MillingTurningEDM | - |
| M 7 Technologies Bending, Welding · ISO 9001 | Youngstown, OH | BendingWelding | ISO 9001 |
| M&M Metals Inc. Bending, Laser, Welding | San Antonio, TX | BendingLaserWelding | - |
| Mace Manufacturing Milling, Welding · ISO 9001, AS9100 | Englewood, CO | MillingWelding | ISO 9001, AS9100 |
| Mach3 Machining Milling, Turning, Welding · ISO 9001 | Cuyahoga Falls, OH | MillingTurningWelding | ISO 9001 |
| Machine Service Inc Welding · ISO 9001 | Green Bay, WI | Welding | ISO 9001 |
| Machine Specialties Co Milling, Turning | Fort Worth, TX | MillingTurning | - |
| 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 | - |
| Machined Products Co Turning, Welding · ISO 9001 | Lancaster, PA | TurningWelding | ISO 9001 |
| Madden Fabrication Milling, Welding | Portland, OR | MillingWelding | - |
| Major Tool & Machine Milling, Turning, Welding · ISO 9001, AS9100, NADCAP | Indianapolis, IN | MillingTurningWelding | ISO 9001, AS9100, NADCAP |
| Make + SHift atx Bending | Austin, TX | Bending | - |
| Mark One Metal Works Turning, Bending, Welding | Sparks, NV | TurningBendingWelding | - |
| Mat-Tech Machining Milling, Turning, Welding | Milwaukee, WI | MillingTurningWelding | - |
| Maumee Valley Fabricators Turning, Welding | Toledo, OH | TurningWelding | - |
| McKenna Metal Bending, Laser, Welding, Waterjet | Portland, OR | BendingLaserWeldingWaterjet | - |
| Mecca Design & Production Welding | Dallas, TX | Welding | - |
| Mecha Inc Milling, Bending, Welding, Waterjet · ISO 9001, ITAR, NADCAP | Raleigh, NC | MillingBendingWeldingWaterjet | ISO 9001, ITAR, NADCAP |
| Megla Manufacturing, Inc. Milling, Bending, Laser, Welding, Waterjet | National City, CA | MillingBendingLaserWeldingWaterjet | - |
| Melton Sheet Metal Bending, Welding | Fresno, CA | BendingWelding | - |
| Merritt Welding & Fabrication Bending, Welding | Denver, CO | BendingWelding | - |
| Metal Arts LLC Welding | Wichita, KS | Welding | - |
| Metal Pro, Inc. Milling, Bending, Welding | Phoenix, AZ | MillingBendingWelding | - |
| Metal Works Precision Machine and Tool, Inc Milling, Turning, Welding | Tucson, AZ | MillingTurningWelding | - |
| Metalcraft Creative Bending, Laser, Welding | Birmingham, AL | BendingLaserWelding | - |
| Metalcraft Inc Bending, Laser, Welding | Boise, ID | BendingLaserWelding | - |
| MetalMania Bending, Laser, Welding | Brooklyn, NY | BendingLaserWelding | - |
| Metals Fabrication Co Milling, Turning, Welding | Airway Heights, WA | MillingTurningWelding | - |
| Metaltech CNC Machining LLC Milling, Turning, Bending | Portsmouth, RI | MillingTurningBending | - |
| Metalworking Group Bending, Welding · CMMC, ISO 9001, ITAR | Cincinnati, OH | BendingWelding | CMMC, ISO 9001, ITAR |
| Metco Metal Fab. Bending, Laser, Welding | Chattanooga, TN | BendingLaserWelding | - |
| Method Mfg Milling · ISO 9001, AS9100, ITAR, CMMC | Buda, TX | Milling | ISO 9001, AS9100, ITAR, CMMC |
| Metzger Machine Co. Milling, Turning, Welding | Cincinnati, OH | MillingTurningWelding | - |