| Hawkins Machine Co Inc Milling, Welding, Grinding | Coventry, RI | MillingWeldingGrinding | - |
| Highline Tool Inc Milling, Turning, Swiss, Grinding | Hillsboro, OR | MillingTurningSwissGrinding | - |
| Highway Machine Co Inc Milling, Welding, Grinding | Princeton, IN | MillingWeldingGrinding | - |
| Hillco Contracting LLC Milling, Turning, Welding, Grinding | Bates City, MO | MillingTurningWeldingGrinding | - |
| Holden on Motorsports, LLC Turning, Laser, Welding, Grinding | Zephyrhills, FL | TurningLaserWeldingGrinding | - |
| Hub Pattern Corp Milling, Turning, Waterjet, EDM, Grinding, Assembly | Roanoke, VA | MillingTurningWaterjetEDMGrindingAssembly | - |
| Huffman Welding & Machine Inc Milling, Turning, Laser, Waterjet, Bending, Welding, EDM, Grinding, Finishing, Assembly · ISO 9001 | Fort Madison, IA | MillingTurningLaserWaterjetBendingWeldingEDMGrindingFinishingAssembly | ISO 9001 |
| Imperial Carbide Inc Milling, Turning, Welding, Stamping, EDM, Grinding, Finishing · ISO 9001 | Meadville, PA | MillingTurningWeldingStampingEDMGrindingFinishing | ISO 9001 |
| Independence Machine & Tool LLC Milling, Turning, Grinding | Madison, IN | MillingTurningGrinding | - |
| Independent Machine Company Milling, Turning, Laser, Welding, Grinding | Escanaba, MI | MillingTurningLaserWeldingGrinding | - |
| Inland Marine Industries Inc Milling, Turning, Waterjet, Punching, Bending, Welding, Grinding, Finishing · ISO 9001, ITAR | Hayward, CA | MillingTurningWaterjetPunchingBendingWeldingGrindingFinishing | ISO 9001, ITAR |
| Insaco Inc Milling, Grinding · ITAR | Quakertown, PA | MillingGrinding | ITAR |
| Inter-Precision Mold Inc Milling, Turning, Welding, EDM, Grinding, Assembly | El Paso, TX | MillingTurningWeldingEDMGrindingAssembly | - |
| Irwin Automation Inc Milling, Turning, Welding, EDM, Grinding | Greensburg, PA | MillingTurningWeldingEDMGrinding | - |
| JC Custom Machining & Design Inc Milling, Turning, Welding, Grinding | Hillsboro, OR | MillingTurningWeldingGrinding | - |
| JC Macelroy Co Inc Milling, Punching, Bending, Welding, Grinding, Assembly | Piscataway, NJ | MillingPunchingBendingWeldingGrindingAssembly | - |
| Joels Machine Shop Inc Milling, Turning, Grinding | El Monte, CA | MillingTurningGrinding | - |
| Johnson Manufacturing Milling, Turning, Grinding · AS9100 | Huntington Beach, CA | MillingTurningGrinding | AS9100 |
| Jonesboro Tool & Die Co Inc Milling, Turning, Laser, Waterjet, Bending, Welding, Stamping, EDM, Grinding · AS9100, ITAR, CMMC | Jonesboro, AR | MillingTurningLaserWaterjetBendingWeldingStampingEDMGrinding | AS9100, ITAR, CMMC |
| K & B Machining Inc Milling, Turning, Laser, Grinding, Finishing · ISO 9001, ITAR | Claremore, OK | MillingTurningLaserGrindingFinishing | ISO 9001, ITAR |
| K & K Precision, Inc Milling, Turning, EDM, Grinding | Mason, OH | MillingTurningEDMGrinding | - |
| Kennebec Technologies Milling, Grinding, Assembly | Augusta, ME | MillingGrindingAssembly | - |
| Kentucky Machine & Tool Co Milling, Turning, Waterjet, Welding, Grinding | Louisville, KY | MillingTurningWaterjetWeldingGrinding | - |
| Keystone Machine & Fab, Inc Milling, Turning, EDM, Grinding | Grafton, OH | MillingTurningEDMGrinding | - |
| KF Precision Honing LLC Milling, Grinding · ITAR | Antigo, WI | MillingGrinding | ITAR |
| Ki Machine Tools & Productions Inc Milling, Turning, Bending, Welding, EDM, Grinding | Loves Park, IL | MillingTurningBendingWeldingEDMGrinding | - |
| Kirsh Manufacturing Inc Milling, Turning, Welding, Grinding, Finishing · ISO 9001, ITAR | Tucson, AZ | MillingTurningWeldingGrindingFinishing | ISO 9001, ITAR |
| KLH Industries Inc Milling, Turning, Waterjet, Bending, Welding, EDM, Grinding, Finishing · ISO 9001, AS9100, ITAR, NADCAP | Germantown, WI | MillingTurningWaterjetBendingWeldingEDMGrindingFinishing | ISO 9001, AS9100, ITAR, NADCAP |
| Kuhn Tool & Die Co Milling, Waterjet, Welding, Stamping, EDM, Grinding | Meadville, PA | MillingWaterjetWeldingStampingEDMGrinding | - |
| Lakes Area Manufacturing Co Milling, Grinding | Shafer, MN | MillingGrinding | - |
| Lam Precision, Inc Milling, Grinding · AS9100 | Anaheim, CA | MillingGrinding | AS9100 |
| Larkin Precision, LLC Laser, Grinding | Kent, WA | LaserGrinding | - |
| Lehi Sheet Metal Turning, Laser, Punching, Bending, Welding, Grinding, Finishing · ISO 9001, AS9100, ITAR | Westborough, MA | TurningLaserPunchingBendingWeldingGrindingFinishing | ISO 9001, AS9100, ITAR |
| Leiss Tool & Die Co Milling, Turning, Bending, Welding, Stamping, EDM, Grinding | Somerset, PA | MillingTurningBendingWeldingStampingEDMGrinding | - |
| LHM Engineering LLC Milling, Swiss, Laser, Waterjet, Stamping, EDM, Grinding, Finishing, Assembly · ISO 13485 | Manchester, MA | MillingSwissLaserWaterjetStampingEDMGrindingFinishingAssembly | ISO 13485 |
| Liberty Precision Works Inc Milling, Turning, EDM, Grinding | Tempe, AZ | MillingTurningEDMGrinding | - |
| Lindor Tool, Inc Milling, Turning, Welding, Casting, Grinding | Saint Croix Falls, WI | MillingTurningWeldingCastingGrinding | - |
| Lindsay Machine Works, Inc Milling, Turning, Laser, Waterjet, Bending, Welding, Grinding | Independence, MO | MillingTurningLaserWaterjetBendingWeldingGrinding | - |
| LL Brown Inc Milling, Grinding | Enola, PA | MillingGrinding | - |
| Loctech Manufacturing Milling, Grinding | Churchville, NY | MillingGrinding | - |
| Long Machine Milling, Turning, Grinding | Temecula, CA | MillingTurningGrinding | - |
| Louis C Morin Co Inc Milling, Turning, Swiss, Welding, Grinding, Finishing, Assembly | North Billerica, MA | MillingTurningSwissWeldingGrindingFinishingAssembly | - |
| LV Swiss Inc Milling, Turning, Swiss, Grinding, Finishing · ISO 9001, AS9100, ITAR, ISO 13485 | La Verkin, UT | MillingTurningSwissGrindingFinishing | ISO 9001, AS9100, ITAR, ISO 13485 |
| Mac Machine Company Milling, Turning, Welding, EDM, Grinding · AS9100, ITAR, NADCAP, CMMC | Baltimore, MD | MillingTurningWeldingEDMGrinding | AS9100, ITAR, NADCAP, CMMC |
| Mac Smith Corp Milling, Turning, Laser, Waterjet, Bending, Welding, Stamping, Grinding | Gardena, CA | MillingTurningLaserWaterjetBendingWeldingStampingGrinding | - |
| Machine Specialties, LLC Milling, Turning, Swiss, Welding, EDM, Grinding, Finishing, Assembly · ISO 9001, AS9100, NADCAP | Whitsett, NC | MillingTurningSwissWeldingEDMGrindingFinishingAssembly | ISO 9001, AS9100, NADCAP |
| Magna Machine & Tool Co Inc Milling, Turning, Waterjet, Welding, EDM, Grinding | New Castle, IN | MillingTurningWaterjetWeldingEDMGrinding | - |
| Magnolia Machine Company Milling, Turning, Welding, EDM, Grinding | Auburndale, FL | MillingTurningWeldingEDMGrinding | - |
| Maritech Machine Inc Milling, Turning, Waterjet, Welding, Grinding, Finishing · ISO 9001, AS9100 | Panama City, FL | MillingTurningWaterjetWeldingGrindingFinishing | ISO 9001, AS9100 |
| Master Machine & Tool Co Inc Welding, EDM, Grinding | Newport News, VA | WeldingEDMGrinding | - |