| Layne West Manufacturing LLC Milling, Swiss, Welding, Grinding | Boise, ID | MillingSwissWeldingGrinding | - |
| Laystrom Manufacturing Company Bending, Laser, Welding | Chicago, IL | BendingLaserWelding | - |
| LD Redmer Milling, Turning, Swiss, Welding, Finishing · ISO 9001, ITAR, NADCAP | Bensenville, IL | MillingTurningSwissWeldingFinishing | ISO 9001, ITAR, NADCAP |
| Le Sueur, Incorporated Welding, Casting · ISO 9001 | Le Sueur, MN | WeldingCasting | ISO 9001 |
| Leanwerks, LLC Milling, Turning, Welding, Casting, Grinding, Assembly · ISO 9001, AS9100, ITAR, CMMC | Ogden, UT | MillingTurningWeldingCastingGrindingAssembly | ISO 9001, AS9100, ITAR, CMMC |
| Lear Machining & Waterjet Inc Milling, Turning, Waterjet, Welding, Grinding · ISO 9001 | Columbus, IN | MillingTurningWaterjetWeldingGrinding | ISO 9001 |
| Legacy Industries Laser, Welding, Stamping · ITAR | Auburn Hills, MI | LaserWeldingStamping | ITAR |
| Lehi Sheet Metal Turning, Laser, Punching, Bending, Welding, Grinding, Finishing · ISO 9001, AS9100, ITAR | Westborough, MA | TurningLaserPunchingBendingWeldingGrindingFinishing | ISO 9001, AS9100, ITAR |
| Leister Machine LLC Milling, Welding | Bedford, PA | MillingWelding | - |
| Lewis Precision & CNC Inc Milling, Turning, Bending, Welding, Grinding, Finishing · ISO 9001, AS9100 | Theodore, AL | MillingTurningBendingWeldingGrindingFinishing | ISO 9001, AS9100 |
| LG Metalworks LLC Milling, Turning, Laser, Waterjet, Welding, EDM, Finishing | Bloomington, IN | MillingTurningLaserWaterjetWeldingEDMFinishing | - |
| Liberty Tool Inc Milling, Turning, Welding, Grinding · ISO 9001, AS9100, ITAR | Sterling Heights, MI | MillingTurningWeldingGrinding | ISO 9001, AS9100, ITAR |
| 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 |
| Lindor Tool, Inc Milling, Turning, Welding, Casting, Grinding | Saint Croix Falls, WI | MillingTurningWeldingCastingGrinding | - |
| LNP Machining Milling, Turning, Welding, Finishing · ISO 9001, AS9100, ITAR, ISO 13485 | San Jose, CA | MillingTurningWeldingFinishing | ISO 9001, AS9100, ITAR, ISO 13485 |
| Lowery's Job Shop Milling, Turning, Laser, Welding, Grinding, Finishing | Saint Louisville, OH | MillingTurningLaserWeldingGrindingFinishing | - |
| 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 | - |
| M & B Machine, Inc Milling, Turning, Swiss, Welding · ISO 9001, AS9100, CMMC | Carlisle, PA | MillingTurningSwissWelding | ISO 9001, AS9100, CMMC |
| M's Machines Milling, Turning, Welding | Monona, IA | MillingTurningWelding | - |
| M&M Machining, Inc Milling, Turning, Welding, Finishing | Ventura, CA | MillingTurningWeldingFinishing | - |
| M&M Metals Inc. Bending, Laser, Welding | San Antonio, TX | BendingLaserWelding | - |
| Mac Machine Company Milling, Turning, Welding, EDM, Grinding · AS9100, ITAR, NADCAP, CMMC | Baltimore, MD | MillingTurningWeldingEDMGrinding | AS9100, ITAR, NADCAP, CMMC |
| Mace Manufacturing Milling, Welding · ISO 9001, AS9100 | Englewood, CO | MillingWelding | ISO 9001, AS9100 |
| Machine & Tool Manufacturing Company Milling, Laser, Waterjet, Welding, Finishing | Adel, GA | MillingLaserWaterjetWeldingFinishing | - |
| Machine Service Inc Welding · ISO 9001 | Green Bay, WI | Welding | ISO 9001 |
| Machine Specialties, LLC Milling, Turning, Swiss, Welding, EDM, Grinding, Finishing, Assembly · ISO 9001, AS9100, NADCAP | Whitsett, NC | MillingTurningSwissWeldingEDMGrindingFinishingAssembly | ISO 9001, AS9100, NADCAP |
| 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 |
| Machining Systems Corporation Milling, Turning, Welding, Grinding, Finishing · ISO 9001 | Crestwood, IL | MillingTurningWeldingGrindingFinishing | ISO 9001 |
| Machining Tech Milling, Turning, Waterjet, Welding, Stamping, EDM, Grinding | Hazle Township, PA | MillingTurningWaterjetWeldingStampingEDMGrinding | - |
| Madden Fabrication Milling, Welding | Portland, OR | MillingWelding | - |
| Magnetic Inspection Laboratory, Inc Milling, Welding, Finishing · ISO 9001, AS9100, NADCAP, ISO 13485 | Elk Grove Village, IL | MillingWeldingFinishing | ISO 9001, AS9100, NADCAP, ISO 13485 |
| Magnum Machine Inc Milling, Turning, Welding, Finishing · ITAR | Raymond, NH | MillingTurningWeldingFinishing | ITAR |
| Magnum Steel Works Milling, Turning, Waterjet, Bending, Welding | Mount Vernon, IL | MillingTurningWaterjetBendingWelding | - |
| Majestic Metals by Fathom Manufacturing Milling, Turning, Bending, Laser, Welding, Waterjet, EDM, Casting, Metal AM · ISO 9001, AS9100, ITAR, ISO 13485 | Denver, CO | MillingTurningBendingLaserWeldingWaterjetEDMCastingMetal AM | ISO 9001, AS9100, ITAR, ISO 13485 |
| Malone Industrial Machine, L.L.C Milling, Turning, Laser, Bending, Welding | Deer Park, TX | MillingTurningLaserBendingWelding | - |
| Malux Machine LLC Milling, Turning, Welding, Grinding | Stratford, CT | MillingTurningWeldingGrinding | - |
| Mannon Metal Works LLC Welding, Forging | Lebanon, MO | WeldingForging | - |
| Manor Tool & Manufacturing Co Milling, Laser, Waterjet, Bending, Welding, Stamping, EDM, Grinding, Finishing · ISO 9001, ITAR | Schiller Park, IL | MillingLaserWaterjetBendingWeldingStampingEDMGrindingFinishing | ISO 9001, ITAR |
| Manufacturing Solutions LLC Milling, Turning, Welding, Finishing | Tulsa, OK | MillingTurningWeldingFinishing | - |
| Marion Manufacturing Milling, Turning, Welding, Stamping, EDM · AS9100 | West Terre Haute, IN | MillingTurningWeldingStampingEDM | AS9100 |
| Marion Precision Tool, Inc Milling, Turning, Waterjet, Bending, Welding, Grinding · ISO 9001 | Ocala, FL | MillingTurningWaterjetBendingWeldingGrinding | ISO 9001 |
| Maritech Machine Inc Milling, Turning, Waterjet, Welding, Grinding, Finishing · ISO 9001, AS9100 | Panama City, FL | MillingTurningWaterjetWeldingGrindingFinishing | ISO 9001, AS9100 |
| Mark One Metal Works Turning, Bending, Welding | Sparks, NV | TurningBendingWelding | - |
| Marsan Inc Bending, Welding, Assembly · ISO 9001 | Germantown, WI | BendingWeldingAssembly | ISO 9001 |
| Martin's Metal Fabrication & Welding, Inc Milling, Turning, Laser, Waterjet, Bending, Welding | Vacaville, CA | MillingTurningLaserWaterjetBendingWelding | - |
| 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 | - |