| J.B. Anderson & Son, Inc Milling, Turning, Welding, Assembly | Irwin, PA | MillingTurningWeldingAssembly | - |
| J.i.t. Manufacturing, Inc Milling, Laser, Punching, Bending, Welding, Finishing, Assembly | Cowpens, SC | MillingLaserPunchingBendingWeldingFinishingAssembly | - |
| Jaco Engineering Milling, Turning, Bending, Welding, EDM, Grinding, Finishing, Assembly · NADCAP | Anaheim, CA | MillingTurningBendingWeldingEDMGrindingFinishingAssembly | NADCAP |
| Jarvis Manufacturing, Inc Milling, Turning, EDM, Assembly · ISO 9001, ITAR | San Jose, CA | MillingTurningEDMAssembly | ISO 9001, ITAR |
| JC Macelroy Co Inc Milling, Punching, Bending, Welding, Grinding, Assembly | Piscataway, NJ | MillingPunchingBendingWeldingGrindingAssembly | - |
| Jeglinski Group Inc Milling, Turning, Welding, EDM, Grinding, Assembly · ISO 9001 | Meadville, PA | MillingTurningWeldingEDMGrindingAssembly | ISO 9001 |
| Jet Helseth Manufacturing Inc Turning, EDM, Finishing, Assembly · ISO 9001, ITAR | Deland, FL | TurningEDMFinishingAssembly | ISO 9001, ITAR |
| JJR Engineering & Fabrication Inc Milling, Turning, Bending, Welding, Stamping, Finishing, Assembly · ISO 9001, AS9100, NADCAP | Woodinville, WA | MillingTurningBendingWeldingStampingFinishingAssembly | ISO 9001, AS9100, NADCAP |
| Jones Co Machining Milling, Turning, Welding, Assembly | Hannibal, MO | MillingTurningWeldingAssembly | - |
| Jones Metal, Inc Milling, Laser, Waterjet, Bending, Welding, Finishing, Assembly | Mankato, MN | MillingLaserWaterjetBendingWeldingFinishingAssembly | - |
| Kad Models and Prototypes Inc Milling, Finishing, Assembly | East Randolph, VT | MillingFinishingAssembly | - |
| Kammerer Dynamics Inc Laser, Bending, Welding, Casting, Finishing, Assembly | Kendallville, IN | LaserBendingWeldingCastingFinishingAssembly | - |
| Kilgore Manufacturing Co Inc Milling, Swiss, Bending, Welding, EDM, Finishing, Assembly · ISO 9001, ITAR | Columbia City, IN | MillingSwissBendingWeldingEDMFinishingAssembly | ISO 9001, ITAR |
| Kiski Precision Industries, LLC Milling, Turning, Welding, Assembly | Leechburg, PA | MillingTurningWeldingAssembly | - |
| KP Manufacturing Milling, Casting, Finishing, Assembly | Spencer, IA | MillingCastingFinishingAssembly | - |
| KSM Industries Inc Bending, Welding, Assembly | Germantown, WI | BendingWeldingAssembly | - |
| Land Sea Air Manufacturing Inc Milling, Turning, Waterjet, Assembly | Westminster, MD | MillingTurningWaterjetAssembly | - |
| Laser Craft Technologies Inc Milling, Turning, Laser, Punching, Bending, Welding, Assembly · ISO 9001 | Gainesville, GA | MillingTurningLaserPunchingBendingWeldingAssembly | ISO 9001 |
| Laserform & Machine Inc Turning, Laser, Punching, Bending, Welding, Finishing, Assembly · ISO 9001 | Columbia, SC | TurningLaserPunchingBendingWeldingFinishingAssembly | ISO 9001 |
| Leanwerks, LLC Milling, Turning, Welding, Casting, Grinding, Assembly · ISO 9001, AS9100, ITAR, CMMC | Ogden, UT | MillingTurningWeldingCastingGrindingAssembly | ISO 9001, AS9100, ITAR, CMMC |
| LHM Engineering LLC Milling, Swiss, Laser, Waterjet, Stamping, EDM, Grinding, Finishing, Assembly · ISO 13485 | Manchester, MA | MillingSwissLaserWaterjetStampingEDMGrindingFinishingAssembly | ISO 13485 |
| Lightning Aerospace LLC Milling, Turning, Bending, Assembly · ISO 9001, AS9100, ITAR | Park City, KS | MillingTurningBendingAssembly | ISO 9001, AS9100, ITAR |
| M & R Engineering Milling, Turning, Swiss, Finishing, Assembly · ISO 9001, AS9100, ITAR, NADCAP | Orange, CA | MillingTurningSwissFinishingAssembly | ISO 9001, AS9100, ITAR, NADCAP |
| M-1 Tool Works, Inc Milling, Turning, EDM, Grinding, Finishing, Assembly · ISO 9001, AS9100 | Mchenry, IL | MillingTurningEDMGrindingFinishingAssembly | ISO 9001, AS9100 |
| M2 Solutions LLC Milling, Assembly | Haverhill, MA | MillingAssembly | - |
| Machine Incorporated Milling, Turning, Swiss, Assembly · ISO 9001, AS9100 | Stoughton, MA | MillingTurningSwissAssembly | ISO 9001, AS9100 |
| Machine Specialties, LLC Milling, Turning, Swiss, Welding, EDM, Grinding, Finishing, Assembly · ISO 9001, AS9100, NADCAP | Whitsett, NC | MillingTurningSwissWeldingEDMGrindingFinishingAssembly | ISO 9001, AS9100, NADCAP |
| Machining Concepts LLC Milling, Turning, Swiss, Assembly · ISO 9001, NADCAP | Germantown, WI | MillingTurningSwissAssembly | ISO 9001, NADCAP |
| Manufacture.us Milling, Turning, Swiss, Laser, Finishing, Assembly | Doral, FL | MillingTurningSwissLaserFinishingAssembly | - |
| Mars Engineering Milling, Turning, Waterjet, EDM, Grinding, Finishing, Assembly | San Leandro, CA | MillingTurningWaterjetEDMGrindingFinishingAssembly | - |
| Marsam Metal Finishing Co Finishing, Assembly | New Britain, CT | FinishingAssembly | - |
| Marsan Inc Bending, Welding, Assembly · ISO 9001 | Germantown, WI | BendingWeldingAssembly | ISO 9001 |
| Mason Dixon Fabrication LLC Milling, Turning, Welding, Assembly | Hanover, PA | MillingTurningWeldingAssembly | - |
| MaxFab Milling, Laser, Punching, Bending, Welding, Stamping, Finishing, Assembly | Madison, AL | MillingLaserPunchingBendingWeldingStampingFinishingAssembly | - |
| McCormick Industries Inc Milling, Turning, Swiss, Welding, Grinding, Finishing, Assembly · ISO 9001 | Appleton, WI | MillingTurningSwissWeldingGrindingFinishingAssembly | ISO 9001 |
| Mercury Aircraft Inc Milling, Laser, Punching, Bending, Welding, Stamping, Assembly · ISO 9001, AS9100, ITAR | Hammondsport, NY | MillingLaserPunchingBendingWeldingStampingAssembly | ISO 9001, AS9100, ITAR |
| 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 |
| Metalquest Unlimited, Inc Milling, Turning, Finishing, Assembly | Hebron, NE | MillingTurningFinishingAssembly | - |
| Metaltech Inc Laser, Bending, Welding, Assembly · AS9100 | Auburn, WA | LaserBendingWeldingAssembly | AS9100 |
| Micro Facture LLC Milling, Turning, EDM, Grinding, Assembly · ISO 9001, ITAR | Lancaster, PA | MillingTurningEDMGrindingAssembly | ISO 9001, ITAR |
| Micro-Matics Inc Milling, Turning, Swiss, Casting, EDM, Grinding, Assembly | Fridley, MN | MillingTurningSwissCastingEDMGrindingAssembly | - |
| Midway Swiss Turn, Inc Milling, Turning, Swiss, Finishing, Assembly · CMMC | Wooster, OH | MillingTurningSwissFinishingAssembly | CMMC |
| Midwest Precision LLC Milling, Turning, Casting, EDM, Grinding, Assembly · ISO 9001, ITAR | Eastlake, OH | MillingTurningCastingEDMGrindingAssembly | ISO 9001, ITAR |
| Mikron Manufacturing Inc Milling, Turning, Laser, Punching, Bending, Welding, Finishing, Assembly · ISO 9001, ITAR | Colorado Springs, CO | MillingTurningLaserPunchingBendingWeldingFinishingAssembly | ISO 9001, ITAR |
| Mitotec Precision, Inc Milling, Turning, Swiss, Assembly · ISO 9001 | Necedah, WI | MillingTurningSwissAssembly | ISO 9001 |
| MK Services Corp Milling, Turning, Swiss, Grinding, Assembly · ISO 9001, ITAR, ISO 13485 | Middleton, MA | MillingTurningSwissGrindingAssembly | ISO 9001, ITAR, ISO 13485 |
| MMG Corp Milling, Turning, Finishing, Assembly · ISO 9001 | Ontario, CA | MillingTurningFinishingAssembly | ISO 9001 |
| Morrison Industries LLC Milling, Turning, Laser, Bending, Welding, Finishing, Assembly | Morrison, TN | MillingTurningLaserBendingWeldingFinishingAssembly | - |
| Motive Machine Works LLC Milling, Turning, Stamping, Finishing, Assembly | Lancaster, PA | MillingTurningStampingFinishingAssembly | - |