| Holden on Motorsports, LLC Turning, Laser, Welding, Grinding | Zephyrhills, FL | TurningLaserWeldingGrinding | - |
| HollyFab Turning, Bending, Laser, Welding, Waterjet | Addison, TX | TurningBendingLaserWeldingWaterjet | - |
| Holzman Machine LLC Milling, Turning, Welding · ITAR | Clearwater, FL | MillingTurningWelding | ITAR |
| Hood Tooling & Machine LLC Milling, Turning, Welding, EDM, Grinding · ISO 9001 | Malvern, AR | MillingTurningWeldingEDMGrinding | ISO 9001 |
| Houston Foundry Manufacturing, L.L.C Milling, Welding, Casting · ISO 9001, AS9100 | Houston, TX | MillingWeldingCasting | ISO 9001, AS9100 |
| Howland Machine Corp Milling, Welding | Niles, OH | MillingWelding | - |
| HTT, Inc Laser, Welding, Stamping, EDM, Grinding, Finishing | Sheboygan, WI | LaserWeldingStampingEDMGrindingFinishing | - |
| Hughes Machine Shop, Inc Milling, Turning, Waterjet, Welding · ISO 9001 | Bogalusa, LA | MillingTurningWaterjetWelding | ISO 9001 |
| Humanetics II of Texas, Inc Milling, Laser, Punching, Bending, Welding, Finishing, Assembly · ISO 9001, AS9100 | Dallas, TX | MillingLaserPunchingBendingWeldingFinishingAssembly | ISO 9001, AS9100 |
| Hunt Enterprises Milling, Turning, Welding | Santa Ana, CA | MillingTurningWelding | - |
| I Auman Machine Co Inc Milling, Turning, Welding | Lebanon, PA | MillingTurningWelding | - |
| I.p. Automation, Inc Milling, Turning, Laser, Waterjet, Bending, Welding, Grinding · ISO 9001 | Colorado Springs, CO | MillingTurningLaserWaterjetBendingWeldingGrinding | ISO 9001 |
| Imperial Carbide Inc Milling, Turning, Welding, Stamping, EDM, Grinding, Finishing · ISO 9001 | Meadville, PA | MillingTurningWeldingStampingEDMGrindingFinishing | ISO 9001 |
| Independent Machine Company Milling, Turning, Laser, Welding, Grinding | Escanaba, MI | MillingTurningLaserWeldingGrinding | - |
| Independent Sheet Metal LLC Punching, Welding | Middletown, OH | PunchingWelding | - |
| Indus Precision Mfg., Inc Milling, Turning, Waterjet, Bending, Welding, Grinding, Finishing, Assembly · ISO 9001, AS9100, ITAR, CMMC | Congers, NY | MillingTurningWaterjetBendingWeldingGrindingFinishingAssembly | ISO 9001, AS9100, ITAR, CMMC |
| Industrial Chrome Inc Milling, Turning, Laser, Bending, Welding, Grinding, Finishing, Assembly · ISO 9001 | Topeka, KS | MillingTurningLaserBendingWeldingGrindingFinishingAssembly | ISO 9001 |
| Industrial Fabricators Milling, Turning, Bending, Welding, Waterjet | Corpus Christi, TX | MillingTurningBendingWeldingWaterjet | - |
| Industrial Metal Finishing Inc Welding, Finishing · AS9100 | Jamestown, NY | WeldingFinishing | AS9100 |
| Industrial Motions Engineering, Inc Milling, Turning, Welding, Grinding, Finishing, Assembly | Wilmington, MA | MillingTurningWeldingGrindingFinishingAssembly | - |
| Industrial Screen & Maintenance, Inc Milling, Turning, Welding, Casting, Grinding · ISO 9001 | Casper, WY | MillingTurningWeldingCastingGrinding | ISO 9001 |
| Infiniti Manufacture Milling, Welding, Finishing | Corona, CA | MillingWeldingFinishing | - |
| Inland Marine Industries Inc Milling, Turning, Waterjet, Punching, Bending, Welding, Grinding, Finishing · ISO 9001, ITAR | Hayward, CA | MillingTurningWaterjetPunchingBendingWeldingGrindingFinishing | ISO 9001, ITAR |
| Innovated Metal Fabrication, Inc Turning, Bending, Laser, Welding | Maplewood, MN | TurningBendingLaserWelding | - |
| Innovation Alley Milling, Turning, Bending, Welding | Fresno, CA | MillingTurningBendingWelding | - |
| InSight Manufacturing Milling, Turning, Welding, Forging, Assembly | Murphys, CA | MillingTurningWeldingForgingAssembly | - |
| Integra Cast Milling, Turning, Welding, Casting, Finishing, Assembly · ISO 9001, NADCAP | New Britain, CT | MillingTurningWeldingCastingFinishingAssembly | ISO 9001, NADCAP |
| Integrated Machining Co Milling, Turning, Welding, EDM, Grinding · ISO 9001, ITAR | Albuquerque, NM | MillingTurningWeldingEDMGrinding | ISO 9001, ITAR |
| Interactive Manufacturing, Inc Milling, Turning, Waterjet, Welding, Finishing, Assembly | Central Point, OR | MillingTurningWaterjetWeldingFinishingAssembly | - |
| Interior Metals Laser, Punching, Bending, Welding, Finishing | Staten Island, NY | LaserPunchingBendingWeldingFinishing | - |
| International Precision Manufacturing LLC Milling, Turning, Welding, EDM, Assembly · ISO 9001, AS9100, ISO 13485 | Houston, TX | MillingTurningWeldingEDMAssembly | ISO 9001, AS9100, ISO 13485 |
| Interstate Manufacturing Company, Inc Milling, Welding · ITAR | Agawam, MA | MillingWelding | ITAR |
| IntoMetal Bending, Laser, Welding, Metal AM | Lincoln, NE | BendingLaserWeldingMetal AM | - |
| Iowa Metal Spinners Milling, Turning, Laser, Welding, Stamping · ISO 9001 | Cedar Falls, IA | MillingTurningLaserWeldingStamping | ISO 9001 |
| IPMI Manufacturing & Engineering Milling, Turning, Welding | Buckner, MO | MillingTurningWelding | - |
| IronStrong Metal Fabrication LLC Milling, Bending, Laser, Welding | Lancaster, PA | MillingBendingLaserWelding | - |
| Irwin Automation Inc Milling, Turning, Welding, EDM, Grinding | Greensburg, PA | MillingTurningWeldingEDMGrinding | - |
| ISCO Manufacturing Solutions Milling, Turning, Waterjet, Bending, Welding, Grinding · ISO 9001, AS9100 | Bend, OR | MillingTurningWaterjetBendingWeldingGrinding | ISO 9001, AS9100 |
| Ital-Tech Machined Products, LLC Milling, Turning, Welding, Grinding · ISO 9001, ITAR | Groveland, MA | MillingTurningWeldingGrinding | ISO 9001, ITAR |
| J & L Precision Manufacturing LLC Bending, Welding, Stamping, Finishing, Assembly · ISO 9001 | Brooklyn Heights, OH | BendingWeldingStampingFinishingAssembly | ISO 9001 |
| J & N Metal Products, LLC Milling, Laser, Bending, Welding, EDM · ISO 9001 | Brazil, IN | MillingLaserBendingWeldingEDM | ISO 9001 |
| J B Tool Die & Engineering Co Inc Milling, Turning, Welding, Stamping, EDM, Grinding · ISO 9001 | Fort Wayne, IN | MillingTurningWeldingStampingEDMGrinding | ISO 9001 |
| J E Fifer Sheet Metal Fabricators Inc Bending, Laser, Welding | Richmond, VA | BendingLaserWelding | - |
| 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 | - |
| J&M Machining Milling, Turning, Welding, Casting, Finishing · ISO 9001 | Norton Shores, MI | MillingTurningWeldingCastingFinishing | ISO 9001 |
| Jacksonville Machine, Inc Milling, Turning, Welding, Grinding · ISO 9001 | Jacksonville, IL | MillingTurningWeldingGrinding | ISO 9001 |
| Jaffa Precision Engineering Inc Milling, Turning, Swiss, Welding, Grinding, Finishing · ISO 9001 | Riverside, CA | MillingTurningSwissWeldingGrindingFinishing | ISO 9001 |
| Jars Inc Milling, Waterjet, Bending, Welding, EDM, Grinding, Finishing | San Fernando, CA | MillingWaterjetBendingWeldingEDMGrindingFinishing | - |
| Jax Fab Shop LLC Welding | Jacksonville, FL | Welding | - |