| LG Metalworks LLC Milling, Turning, Laser, Waterjet, Welding, EDM, Finishing | Bloomington, IN | MillingTurningLaserWaterjetWeldingEDMFinishing | - |
| Liberty CNC LLC Milling, Turning, Finishing · ISO 9001 | Cocolalla, ID | MillingTurningFinishing | ISO 9001 |
| Linear Machining Technology LLC Milling, Turning, EDM, Grinding, Finishing · ISO 9001 | Irwin, PA | MillingTurningEDMGrindingFinishing | ISO 9001 |
| Lively Machine Milling, Turning, Bending, Finishing | Evansville, IN | MillingTurningBendingFinishing | - |
| LNP Machining Milling, Turning, Welding, Finishing · ISO 9001, AS9100, ITAR, ISO 13485 | San Jose, CA | MillingTurningWeldingFinishing | ISO 9001, AS9100, ITAR, ISO 13485 |
| Locdown Com Laser, Bending, Welding, Finishing | Brea, CA | LaserBendingWeldingFinishing | - |
| Lomar Machine & Tool Co Milling, Turning, Laser, Bending, Welding, Casting, EDM, Grinding, Finishing · ISO 9001 | Horton, MI | MillingTurningLaserBendingWeldingCastingEDMGrindingFinishing | ISO 9001 |
| Longleaf Machining LLC Turning, Finishing · ISO 9001, ITAR | Brewton, AL | TurningFinishing | ISO 9001, ITAR |
| Loutech LLC Milling, Turning, Swiss, Finishing · ISO 9001, AS9100, ITAR | Chino, CA | MillingTurningSwissFinishing | ISO 9001, AS9100, ITAR |
| LP Precision, Inc Milling, Turning, Grinding, Finishing | Santa Clara, CA | MillingTurningGrindingFinishing | - |
| 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-1 Tool Works, Inc Milling, Turning, EDM, Grinding, Finishing, Assembly · ISO 9001, AS9100 | Mchenry, IL | MillingTurningEDMGrindingFinishingAssembly | ISO 9001, AS9100 |
| M&M Machining, Inc Milling, Turning, Welding, Finishing | Ventura, CA | MillingTurningWeldingFinishing | - |
| Machine & Tool Manufacturing Company Milling, Laser, Waterjet, Welding, Finishing | Adel, GA | MillingLaserWaterjetWeldingFinishing | - |
| Machineworks Manufacturing Milling, Turning, Laser, Bending, Welding, Finishing · ISO 9001, AS9100, ITAR | Northridge, CA | MillingTurningLaserBendingWeldingFinishing | ISO 9001, AS9100, ITAR |
| Magna Machining, Inc Milling, Turning, Finishing | Richfield, NC | MillingTurningFinishing | - |
| Magnetic Inspection Laboratory, Inc Milling, Welding, Finishing · ISO 9001, AS9100, NADCAP, ISO 13485 | Elk Grove Village, IL | MillingWeldingFinishing | ISO 9001, AS9100, NADCAP, ISO 13485 |
| Manufacture.us Milling, Turning, Swiss, Laser, Finishing, Assembly | Doral, FL | MillingTurningSwissLaserFinishingAssembly | - |
| Manufacturing Solutions LLC Milling, Turning, Welding, Finishing | Tulsa, OK | MillingTurningWeldingFinishing | - |
| Mapp Technologies, L.L.C Milling, Welding, Grinding, Finishing · NADCAP, CMMC | Joplin, MO | MillingWeldingGrindingFinishing | NADCAP, CMMC |
| Marinette Machine LLC Turning, Welding, Grinding, Finishing | Marinette, WI | TurningWeldingGrindingFinishing | - |
| Maritech Machine Inc Milling, Turning, Waterjet, Welding, Grinding, Finishing · ISO 9001, AS9100 | Panama City, FL | MillingTurningWaterjetWeldingGrindingFinishing | ISO 9001, AS9100 |
| Mars Engineering Milling, Turning, Waterjet, EDM, Grinding, Finishing, Assembly | San Leandro, CA | MillingTurningWaterjetEDMGrindingFinishingAssembly | - |
| 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 |
| Marvel Manufacturing Milling, Turning, Swiss, Welding, EDM, Grinding, Finishing | Lewiston, ID | MillingTurningSwissWeldingEDMGrindingFinishing | - |
| Maryland Greater Tool & Manufacturing Milling, Turning, Waterjet, Welding, Grinding, Finishing | Mountain Lake Park, MD | MillingTurningWaterjetWeldingGrindingFinishing | - |
| Masters Machine Company Milling, Turning, Swiss, Grinding, Finishing · ISO 9001, ITAR | Bristol, ME | MillingTurningSwissGrindingFinishing | ISO 9001, ITAR |
| Masterson Industries, Inc Turning, Grinding, Finishing | Taylor, TX | TurningGrindingFinishing | - |
| MaxFab Milling, Laser, Punching, Bending, Welding, Stamping, Finishing, Assembly | Madison, AL | MillingLaserPunchingBendingWeldingStampingFinishingAssembly | - |
| Maxsteel Fabrication, LLC Milling, Turning, Laser, Welding, Finishing | Paris, TN | MillingTurningLaserWeldingFinishing | - |
| McCallin Steel Storage Systems, Inc Milling, Punching, Welding, Finishing | Commerce City, CO | MillingPunchingWeldingFinishing | - |
| McCormick Industries Inc Milling, Turning, Swiss, Welding, Grinding, Finishing, Assembly · ISO 9001 | Appleton, WI | MillingTurningSwissWeldingGrindingFinishingAssembly | ISO 9001 |
| Meridian Manufacturing Inc Milling, Turning, Laser, Welding, EDM, Grinding, Finishing | Ballston Spa, NY | MillingTurningLaserWeldingEDMGrindingFinishing | - |
| Merit Industries Milling, Turning, Laser, Waterjet, Welding, EDM, Grinding, Finishing · AS9100, ITAR, NADCAP, CMMC | Erie, PA | MillingTurningLaserWaterjetWeldingEDMGrindingFinishing | AS9100, ITAR, NADCAP, CMMC |
| 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 Essence Inc Milling, Turning, Swiss, Finishing, Assembly · ISO 9001, AS9100, ITAR | Longwood, FL | MillingTurningSwissFinishingAssembly | ISO 9001, AS9100, ITAR |
| Metal Workz L.L.C Milling, Turning, Laser, Bending, Welding, Finishing | Albany, KY | MillingTurningLaserBendingWeldingFinishing | - |
| Metalbuilt LLC Milling, Turning, Laser, Welding, Stamping, Finishing · ISO 9001, AS9100, IATF 16949 | Chesterfield, MI | MillingTurningLaserWeldingStampingFinishing | ISO 9001, AS9100, IATF 16949 |
| Metalmasters Milling, Turning, Bending, Welding, Finishing | Brighton, CO | MillingTurningBendingWeldingFinishing | - |
| MF Engineering Company, Inc Milling, Turning, Swiss, Welding, Grinding, Finishing · ISO 9001, NADCAP | Bristol, RI | MillingTurningSwissWeldingGrindingFinishing | ISO 9001, NADCAP |
| Micro-Tec, Inc Milling, Turning, Welding, EDM, Finishing · ISO 9001, AS9100 | Chatsworth, CA | MillingTurningWeldingEDMFinishing | ISO 9001, AS9100 |
| Mid-Continent Machining Inc Milling, Turning, Welding, Finishing | Kansas City, KS | MillingTurningWeldingFinishing | - |
| Midway Machine & Instrument Company Inc Milling, Turning, EDM, Finishing · ISO 9001 | South Houston, TX | MillingTurningEDMFinishing | ISO 9001 |
| 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 |
| Milo Engineering Milling, Turning, Grinding, Finishing · ISO 9001 | Torrance, CA | MillingTurningGrindingFinishing | ISO 9001 |
| Mimic Manufacturing, LLC Welding, Finishing | Heavener, OK | WeldingFinishing | - |