| Honeycutt Manufacturing Inc Milling, Turning, Swiss, Stamping, Grinding, Finishing | Mukilteo, WA | MillingTurningSwissStampingGrindingFinishing | - |
| Horizon Tech Industries Inc Milling, Turning, Swiss, Finishing | Fort Worth, TX | MillingTurningSwissFinishing | - |
| Huntington Plating, Inc Milling, Welding, Grinding, Finishing | Huntington, WV | MillingWeldingGrindingFinishing | - |
| IFT Worldwide Milling, Stamping, Finishing | South Bend, IN | MillingStampingFinishing | - |
| Industrial Motions Engineering, Inc Milling, Turning, Welding, Grinding, Finishing, Assembly | Wilmington, MA | MillingTurningWeldingGrindingFinishingAssembly | - |
| Industrial Specialty Co Inc Turning, Finishing | Montgomery, AL | TurningFinishing | - |
| Integrity Welding & Fabrication LLC Laser, Waterjet, Welding, Finishing | Colorado Springs, CO | LaserWaterjetWeldingFinishing | - |
| Interior Metals Laser, Punching, Bending, Welding, Finishing | Staten Island, NY | LaserPunchingBendingWeldingFinishing | - |
| J&D Custom Finishing | Holden, MO | Finishing | - |
| Jaco Engineering Milling, Turning, Bending, Welding, EDM, Grinding, Finishing, Assembly · NADCAP | Anaheim, CA | MillingTurningBendingWeldingEDMGrindingFinishingAssembly | NADCAP |
| Jem Custom Products, Inc Milling, Finishing | Wauconda, IL | MillingFinishing | - |
| JG Innovations, Inc Finishing | Janesville, WI | Finishing | - |
| Johnson Brass & Machine Foundry Inc Casting, Finishing | Saukville, WI | CastingFinishing | - |
| Jones Metal, Inc Milling, Laser, Waterjet, Bending, Welding, Finishing, Assembly | Mankato, MN | MillingLaserWaterjetBendingWeldingFinishingAssembly | - |
| Just One More Part, LLC Bending, Welding, Finishing | Pottstown, PA | BendingWeldingFinishing | - |
| Kad Models and Prototypes Inc Milling, Finishing, Assembly | East Randolph, VT | MillingFinishingAssembly | - |
| Kennley Corp Milling, Turning, Grinding, Finishing | North Chesterfield, VA | MillingTurningGrindingFinishing | - |
| Kinross Fab & Machine Inc Milling, Turning, Laser, Welding, Grinding, Finishing | Kincheloe, MI | MillingTurningLaserWeldingGrindingFinishing | - |
| Kte Holdings LLC Milling, Turning, Welding, Grinding, Finishing | Mableton, GA | MillingTurningWeldingGrindingFinishing | - |
| Lai International Inc Milling, Laser, Waterjet, Welding, Metal AM, EDM, Finishing · NADCAP | Westminster, MD | MillingLaserWaterjetWeldingMetal AMEDMFinishing | NADCAP |
| Lakecity Industries Holding Inc Finishing | Lake City, PA | Finishing | - |
| Lakehouse Industries Milling, Turning, Finishing | Woodland, WA | MillingTurningFinishing | - |
| Laser Precision Cutting Inc Laser, Waterjet, Bending, Welding, Finishing | Weaverville, NC | LaserWaterjetBendingWeldingFinishing | - |
| Latitude Corp Milling, Waterjet, Punching, Bending, Welding, Stamping, Grinding, Finishing · AS9100 | Verona, WI | MillingWaterjetPunchingBendingWeldingStampingGrindingFinishing | AS9100 |
| LG Metalworks LLC Milling, Turning, Laser, Waterjet, Welding, EDM, Finishing | Bloomington, IN | MillingTurningLaserWaterjetWeldingEDMFinishing | - |
| Locdown Com Laser, Bending, Welding, Finishing | Brea, CA | LaserBendingWeldingFinishing | - |
| Loughmiller Machine, Tool & Design Milling, Turning, Waterjet, Welding, EDM, Finishing | Loogootee, IN | MillingTurningWaterjetWeldingEDMFinishing | - |
| Lowell Manufacturing Company Finishing | Pacific, MO | Finishing | - |
| Lowery's Job Shop Milling, Turning, Laser, Welding, Grinding, Finishing | Saint Louisville, OH | MillingTurningLaserWeldingGrindingFinishing | - |
| LP Precision, Inc Milling, Turning, Grinding, Finishing | Santa Clara, CA | MillingTurningGrindingFinishing | - |
| Luke Manufacturing Co Casting, Finishing | Wadsworth, OH | CastingFinishing | - |
| M&M Full Service Machine Shop Milling, Bending, Welding, Grinding, Finishing | Satellite Beach, FL | MillingBendingWeldingGrindingFinishing | - |
| Machine & Tool Manufacturing Company Milling, Laser, Waterjet, Welding, Finishing | Adel, GA | MillingLaserWaterjetWeldingFinishing | - |
| 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 |
| Marsam Metal Finishing Co Finishing, Assembly | New Britain, CT | FinishingAssembly | - |
| Maryland Greater Tool & Manufacturing Milling, Turning, Waterjet, Welding, Grinding, Finishing | Mountain Lake Park, MD | MillingTurningWaterjetWeldingGrindingFinishing | - |
| Masterson Industries, Inc Turning, Grinding, Finishing | Taylor, TX | TurningGrindingFinishing | - |
| Maxsteel Fabrication, LLC Milling, Turning, Laser, Welding, Finishing | Paris, TN | MillingTurningLaserWeldingFinishing | - |
| McCallin Steel Storage Systems, Inc Milling, Punching, Welding, Finishing | Commerce City, CO | MillingPunchingWeldingFinishing | - |
| Menze Precision Machining, LLC Milling, Turning, Bending, Welding, EDM, Grinding, Finishing | Winter Haven, FL | MillingTurningBendingWeldingEDMGrindingFinishing | - |
| Met International Trading Company, Inc Laser, Punching, Bending, Welding, Finishing | Houston, TX | LaserPunchingBendingWeldingFinishing | - |
| Metal Workz L.L.C Milling, Turning, Laser, Bending, Welding, Finishing | Albany, KY | MillingTurningLaserBendingWeldingFinishing | - |
| Mico Welding & Machining, Inc Milling, Turning, Welding, Finishing | Nine Mile Falls, WA | MillingTurningWeldingFinishing | - |
| Micro Machine & Electronics, Inc Milling, Turning, Welding, Grinding, Finishing, Assembly · ITAR | Leominster, MA | MillingTurningWeldingGrindingFinishingAssembly | ITAR |
| Mid-Continent Machining Inc Milling, Turning, Welding, Finishing | Kansas City, KS | MillingTurningWeldingFinishing | - |
| Midwest Industrial Metal Fabrication Inc Milling, Turning, Punching, Bending, Welding, Stamping, Finishing | Huntington, IN | MillingTurningPunchingBendingWeldingStampingFinishing | - |
| Midwest Machine & Tool, Inc Milling, Turning, Welding, EDM, Grinding, Finishing | Columbus, NE | MillingTurningWeldingEDMGrindingFinishing | - |
| Midwest Precision Machining Milling, Turning, Swiss, Grinding, Finishing · AS9100, NADCAP | Monticello, MN | MillingTurningSwissGrindingFinishing | AS9100, NADCAP |
| Milner's Anodizing Finishing · NADCAP | Santa Rosa, CA | Finishing | NADCAP |