| Lindsay Machine Works, Inc Milling, Turning, Laser, Waterjet, Bending, Welding, Grinding | Independence, MO | MillingTurningLaserWaterjetBendingWeldingGrinding | - |
| LM Gill Welding & Manufacturing LLC Milling, Welding · ISO 9001, AS9100, ITAR, NADCAP | Manchester, CT | MillingWelding | ISO 9001, AS9100, ITAR, NADCAP |
| Lowell Manufacturing Company Finishing | Pacific, MO | Finishing | - |
| LV Swiss Inc Milling, Turning, Swiss, Grinding, Finishing · ISO 9001, AS9100, ITAR, ISO 13485 | La Verkin, UT | MillingTurningSwissGrindingFinishing | ISO 9001, AS9100, ITAR, ISO 13485 |
| M W M Services, Inc Milling, Welding, EDM | Riviera Beach, FL | MillingWeldingEDM | - |
| M-1 Tool Works, Inc Milling, Turning, EDM, Grinding, Finishing, Assembly · ISO 9001, AS9100 | Mchenry, IL | MillingTurningEDMGrindingFinishingAssembly | ISO 9001, AS9100 |
| Machine Craft Northwest Inc Milling, Turning, Welding | Lebanon, OR | MillingTurningWelding | - |
| Machinewell, Inc Milling, Welding · ISO 9001 | Grygla, MN | MillingWelding | ISO 9001 |
| Machineworks Manufacturing Milling, Turning, Laser, Bending, Welding, Finishing · ISO 9001, AS9100, ITAR | Northridge, CA | MillingTurningLaserBendingWeldingFinishing | ISO 9001, AS9100, ITAR |
| Machworks LLC Welding | Thomaston, GA | Welding | - |
| Magnum Steel Works Milling, Turning, Waterjet, Bending, Welding | Mount Vernon, IL | MillingTurningWaterjetBendingWelding | - |
| Mannon Metal Works LLC Welding, Forging | Lebanon, MO | WeldingForging | - |
| Mark One Metal Works Turning, Bending, Welding | Sparks, NV | TurningBendingWelding | - |
| Matern Metal Works, Inc Punching, Bending, Welding | Mansfield, OH | PunchingBendingWelding | - |
| Matrix Metalworks LLC Milling, Welding · ISO 9001 | Sugar Land, TX | MillingWelding | ISO 9001 |
| MCW Certified Welding Ltd Punching, Bending, Welding | Delta, OH | PunchingBendingWelding | - |
| Melting Point Metalworks LLC Laser, Bending, Welding | Brownsburg, IN | LaserBendingWelding | - |
| Mercury Machine Works LLC Milling, Turning, Laser, Finishing · ISO 9001, ITAR | Spring, TX | MillingTurningLaserFinishing | ISO 9001, ITAR |
| Merritt Welding & Fabrication Bending, Welding | Denver, CO | BendingWelding | - |
| Metal Works Precision Machine and Tool, Inc Milling, Turning, Welding | Tucson, AZ | MillingTurningWelding | - |
| Metal Workz L.L.C Milling, Turning, Laser, Bending, Welding, Finishing | Albany, KY | MillingTurningLaserBendingWeldingFinishing | - |
| Metalworking Group Bending, Welding · CMMC, ISO 9001, ITAR | Cincinnati, OH | BendingWelding | CMMC, ISO 9001, ITAR |
| Metwerks LLC Turning, Waterjet, Welding | Rapid City, SD | TurningWaterjetWelding | - |
| Middletown Industrial Technologies, LLC Milling, Turning, Welding, Stamping, Assembly | Middletown, OH | MillingTurningWeldingStampingAssembly | - |
| Midway Machine & Instrument Company Inc Milling, Turning, EDM, Finishing · ISO 9001 | South Houston, TX | MillingTurningEDMFinishing | ISO 9001 |
| Midwest Industrial Metal Fabrication Inc Milling, Turning, Punching, Bending, Welding, Stamping, Finishing | Huntington, IN | MillingTurningPunchingBendingWeldingStampingFinishing | - |
| Midwest Tool Inc Milling, Turning, Welding, EDM, Grinding | Joplin, MO | MillingTurningWeldingEDMGrinding | - |
| Milco Wire EDM Inc Waterjet, Stamping, EDM · AS9100, ITAR, NADCAP | Huntington Beach, CA | WaterjetStampingEDM | AS9100, ITAR, NADCAP |
| Mills Machine Works Inc Milling, Turning, Welding, Grinding | Lawrence, MA | MillingTurningWeldingGrinding | - |
| Millwood Metalworks Punching, Bending, Welding | Freeport, MN | PunchingBendingWelding | - |
| Milwaukee Metal Products Co Bending, Welding, Stamping | Milwaukee, WI | BendingWeldingStamping | - |
| Morena Welding Inc Welding | San Diego, CA | Welding | - |
| Mountain Machine Works Milling, Turning, Welding · ISO 9001, ITAR | Auburn, ME | MillingTurningWelding | ISO 9001, ITAR |
| Mountain View Machine and Welding Milling, Turning, Waterjet, Welding, EDM | Logan, UT | MillingTurningWaterjetWeldingEDM | - |
| MRW Fabrication LLC Bending, Welding | Independence, MO | BendingWelding | - |
| Mumford Micro Machine Works, LLC Milling, Turning, Swiss, EDM, Grinding · ITAR | Nokomis, FL | MillingTurningSwissEDMGrinding | ITAR |
| Nassau Metal Works LLC Welding | Yulee, FL | Welding | - |
| National K Works Partnership Ltd Milling, Welding, EDM, Assembly | Houston, TX | MillingWeldingEDMAssembly | - |
| New England CNC, Inc Milling, Finishing | Hamden, CT | MillingFinishing | - |
| NEW Industries Milling, Turning, Welding · ISO 9001 | Sturgeon Bay, WI | MillingTurningWelding | ISO 9001 |
| New World Machining Inc Milling, Turning, Welding | San Jose, CA | MillingTurningWelding | - |
| Newhart Products II Inc Waterjet, Stamping | Milford, CT | WaterjetStamping | - |
| Newport Mfg Laser, Welding | Newcastle, WA | LaserWelding | - |
| Nocturnal Welding Welding | Camarillo, CA | Welding | - |
| Northway Mathers Inc Milling, Turning, Waterjet, Bending, Welding, Finishing | Mukilteo, WA | MillingTurningWaterjetBendingWeldingFinishing | - |
| Northwest Machining & Manufacturing Inc Milling, Turning, Welding, EDM · ISO 9001 | Meridian, ID | MillingTurningWeldingEDM | ISO 9001 |
| Northwest Steel Fab, Inc Milling, Punching, Bending, Welding | Deer Park, WA | MillingPunchingBendingWelding | - |
| NW4S Inc Milling, Punching, Bending, Welding, Stamping, EDM, Finishing · ISO 9001, AS9100 | Lewiston, ID | MillingPunchingBendingWeldingStampingEDMFinishing | ISO 9001, AS9100 |
| O. W. Landergren, Inc Milling, Laser, Punching, Bending, Welding, Stamping, EDM, Grinding, Finishing | Pittsfield, MA | MillingLaserPunchingBendingWeldingStampingEDMGrindingFinishing | - |
| Omni Machine Works Inc Milling, Turning, Welding, EDM, Grinding | Covington, GA | MillingTurningWeldingEDMGrinding | - |