| Joined Alloys Welding, EDM, Assembly · ISO 9001, NADCAP | Phoenix, AZ | WeldingEDMAssembly | ISO 9001, NADCAP |
| Jones Co Machining Milling, Turning, Welding, Assembly | Hannibal, MO | MillingTurningWeldingAssembly | - |
| Jones Metal, Inc Milling, Laser, Waterjet, Bending, Welding, Finishing, Assembly | Mankato, MN | MillingLaserWaterjetBendingWeldingFinishingAssembly | - |
| Justified Performance LLC Laser, Bending, Welding, Finishing, Assembly · ISO 9001 | Rocklin, CA | LaserBendingWeldingFinishingAssembly | ISO 9001 |
| 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 | - |
| Kocsis Brothers Machine Company Welding, Assembly | Alsip, IL | WeldingAssembly | - |
| KP Manufacturing Milling, Casting, Finishing, Assembly | Spencer, IA | MillingCastingFinishingAssembly | - |
| Krametech, Inc Milling, Finishing, Assembly | Lake Zurich, IL | MillingFinishingAssembly | - |
| KSM Industries Inc Bending, Welding, Assembly | Germantown, WI | BendingWeldingAssembly | - |
| Lark Industries Turning, Waterjet, Welding, Assembly · ISO 9001, ISO 13485 | El Paso, TX | TurningWaterjetWeldingAssembly | ISO 9001, ISO 13485 |
| Laser Metal Fabrication Laser, Bending, Welding, Assembly | Twin Falls, ID | LaserBendingWeldingAssembly | - |
| Laserform & Machine Inc Turning, Laser, Punching, Bending, Welding, Finishing, Assembly · ISO 9001 | Columbia, SC | TurningLaserPunchingBendingWeldingFinishingAssembly | ISO 9001 |
| LHM Engineering LLC Milling, Swiss, Laser, Waterjet, Stamping, EDM, Grinding, Finishing, Assembly · ISO 13485 | Manchester, MA | MillingSwissLaserWaterjetStampingEDMGrindingFinishingAssembly | ISO 13485 |
| Linita Design & Mfg. Corp Turning, Welding, Assembly | Lackawanna, NY | TurningWeldingAssembly | - |
| Lodolce Machine Co, Inc Milling, Turning, Laser, Welding, EDM, Assembly · ISO 9001, AS9100 | Saugerties, NY | MillingTurningLaserWeldingEDMAssembly | ISO 9001, AS9100 |
| Louis C Morin Co Inc Milling, Turning, Swiss, Welding, Grinding, Finishing, Assembly | North Billerica, MA | MillingTurningSwissWeldingGrindingFinishingAssembly | - |
| Mac Products, Inc Milling, Waterjet, Bending, Welding, Assembly · ISO 9001 | Kearny, NJ | MillingWaterjetBendingWeldingAssembly | ISO 9001 |
| Mach Machine Inc Turning, Welding, Stamping, Casting, EDM, Assembly · ISO 9001, ITAR | Hudson, MA | TurningWeldingStampingCastingEDMAssembly | ISO 9001, ITAR |
| Machine Incorporated Milling, Turning, Swiss, Assembly · ISO 9001, AS9100 | Stoughton, MA | MillingTurningSwissAssembly | ISO 9001, AS9100 |
| Machine Repair & Design Milling, Turning, Waterjet, Welding, Finishing, Assembly · AS9100 | Sumner, WA | MillingTurningWaterjetWeldingFinishingAssembly | AS9100 |
| 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 |
| Marx Digital Manufacturing Inc Milling, Turning, Welding, Assembly | Santa Clara, CA | MillingTurningWeldingAssembly | - |
| Mass Precision Inc Welding, Assembly · ISO 9001, ISO 13485 | San Jose, CA | WeldingAssembly | ISO 9001, ISO 13485 |
| 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 |
| Mdi Manufacturing Inc Milling, Turning, Welding, Grinding, Assembly · ISO 9001 | Lakewood, NJ | MillingTurningWeldingGrindingAssembly | 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 |
| Metalcraft Industries, Inc Welding, Stamping, Finishing, Assembly · CMMC | Denver, CO | WeldingStampingFinishingAssembly | CMMC |
| Metalquest Unlimited, Inc Milling, Turning, Finishing, Assembly | Hebron, NE | MillingTurningFinishingAssembly | - |
| Metplas Inc Milling, Turning, Waterjet, Punching, Bending, Assembly · ISO 9001 | Natrona Heights, PA | MillingTurningWaterjetPunchingBendingAssembly | ISO 9001 |
| Micro-Matics Inc Milling, Turning, Swiss, Casting, EDM, Grinding, Assembly | Fridley, MN | MillingTurningSwissCastingEDMGrindingAssembly | - |
| 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 |
| 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 |
| MM Industries Tech LLC Laser, Punching, Bending, Welding, Assembly | Stanwood, WA | LaserPunchingBendingWeldingAssembly | - |
| MMG Corp Milling, Turning, Finishing, Assembly · ISO 9001 | Ontario, CA | MillingTurningFinishingAssembly | ISO 9001 |
| Modern Forge Indiana LLC Turning, Welding, Casting, Forging, Assembly · ISO 9001, AS9100, NADCAP | Merrillville, IN | TurningWeldingCastingForgingAssembly | ISO 9001, AS9100, NADCAP |
| Modus Advanced Milling, Waterjet, Finishing, Assembly · ISO 9001, AS9100, ITAR, CMMC | Carlsbad, CA | MillingWaterjetFinishingAssembly | ISO 9001, AS9100, ITAR, CMMC |
| Moore Tool Company, Inc Stamping, Grinding, Finishing, Assembly · ISO 9001, AS9100 | Bridgeport, CT | StampingGrindingFinishingAssembly | ISO 9001, AS9100 |
| Mountain CNC Milling, Turning, Waterjet, Welding, Grinding, Finishing, Assembly · ITAR, CMMC | Loveland, CO | MillingTurningWaterjetWeldingGrindingFinishingAssembly | ITAR, CMMC |
| MST Manufacturing LLC Milling, Turning, Bending, Welding, Assembly · ISO 9001, AS9100, ITAR, CMMC | Claremore, OK | MillingTurningBendingWeldingAssembly | ISO 9001, AS9100, ITAR, CMMC |