| High Steel Structures LLC Welding | Lancaster, PA | Welding | - |
| High Tech Machine II Co Limited Milling, Turning, Welding, EDM | Houston, TX | MillingTurningWeldingEDM | - |
| Hill Aerosystems Inc Milling, Turning, Waterjet, Punching, Bending, Welding, Stamping, EDM, Assembly · AS9100 | Enumclaw, WA | MillingTurningWaterjetPunchingBendingWeldingStampingEDMAssembly | AS9100 |
| Hilton Tool Milling, Turning, Welding, EDM, Grinding · ISO 9001, AS9100 | Clackamas, OR | MillingTurningWeldingEDMGrinding | ISO 9001, AS9100 |
| Hitech Metalfab Inc Bending, Welding · ISO 9001 | Santa Clara, CA | BendingWelding | ISO 9001 |
| Hogin Machine, Inc Milling, Turning, Swiss, Waterjet, Bending, Welding | Santa Ana, CA | MillingTurningSwissWaterjetBendingWelding | - |
| Holbrook Laser, Welding | Franklin, IN | LaserWelding | - |
| 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 |
| Howland Machine Corp Milling, Welding | Niles, OH | MillingWelding | - |
| Huntington Plating, Inc Milling, Welding, Grinding, Finishing | Huntington, WV | MillingWeldingGrindingFinishing | - |
| Huntington Steel & Supply Co Bending, Welding | Huntington, WV | BendingWelding | - |
| I.p. Automation, Inc Milling, Turning, Laser, Waterjet, Bending, Welding, Grinding · ISO 9001 | Colorado Springs, CO | MillingTurningLaserWaterjetBendingWeldingGrinding | ISO 9001 |
| Ideal Technology Corp Milling, Turning, Welding, Casting, Metal AM, Grinding · ISO 9001 | Shelby Township, MI | MillingTurningWeldingCastingMetal AMGrinding | ISO 9001 |
| Independent Machine Company Milling, Turning, Laser, Welding, Grinding | Escanaba, MI | MillingTurningLaserWeldingGrinding | - |
| Infiniti Manufacture Milling, Welding, Finishing | Corona, CA | MillingWeldingFinishing | - |
| Inno-Tec Welding & Fabrication LLC Welding | Springfield, OH | Welding | - |
| Innovation Alley Milling, Turning, Bending, Welding | Fresno, CA | MillingTurningBendingWelding | - |
| Innovative Manufacturing and Design, LLC Milling, Welding, EDM · ISO 9001, ITAR | Greenville, SC | MillingWeldingEDM | 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 |
| 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 |
| 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 |
| J & L Precision Manufacturing LLC Bending, Welding, Stamping, Finishing, Assembly · ISO 9001 | Brooklyn Heights, OH | BendingWeldingStampingFinishingAssembly | ISO 9001 |
| J Mark Co Milling, Turning, Laser, Punching, Bending, Welding, Finishing, Assembly · ISO 9001, ITAR | Vista, CA | MillingTurningLaserPunchingBendingWeldingFinishingAssembly | ISO 9001, ITAR |
| J Newell Corp Milling, Welding | Arlington, WA | MillingWelding | - |
| 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 |
| Jaguar Precision Machine, LLC. Milling, Turning, Bending, Welding, Waterjet, Stamping, Metal AM · ISO 9001, AS9100, ITAR | Albuquerque, NM | MillingTurningBendingWeldingWaterjetStampingMetal AM | ISO 9001, AS9100, ITAR |
| James Tool Machine & Engineering Inc Milling, Turning, Welding, EDM, Grinding, Finishing · ISO 9001, AS9100 | Morganton, NC | MillingTurningWeldingEDMGrindingFinishing | ISO 9001, AS9100 |
| Jax Fab Shop LLC Welding | Jacksonville, FL | Welding | - |
| JBC Machine Inc Milling, Turning, Welding, Finishing | Hortonville, WI | MillingTurningWeldingFinishing | - |
| JC Macelroy Co Inc Milling, Punching, Bending, Welding, Grinding, Assembly | Piscataway, NJ | MillingPunchingBendingWeldingGrindingAssembly | - |
| JC Machine, Inc Milling, Turning, Swiss, Laser, Bending, Welding | Lakeland, FL | MillingTurningSwissLaserBendingWelding | - |
| JDM Machining Inc Milling, Turning, Swiss, Bending, Welding, EDM, Grinding · ISO 9001, AS9100 | Staples, MN | MillingTurningSwissBendingWeldingEDMGrinding | ISO 9001, AS9100 |
| Jep Manufacturing LLC Milling, Turning, Welding · ISO 9001 | Rosenberg, TX | MillingTurningWelding | ISO 9001 |
| Jergens Inc Milling, Welding · ISO 9001, AS9100 | Cleveland, OH | MillingWelding | ISO 9001, AS9100 |
| Jerl Machine Inc Milling, Turning, Welding, Casting, EDM, Grinding, Assembly · ISO 9001 | Perrysburg, OH | MillingTurningWeldingCastingEDMGrindingAssembly | ISO 9001 |
| JK Pulley Co Inc Milling, Turning, Welding | Saint Louis, MO | MillingTurningWelding | - |
| JMC Acquisition LLC Milling, Turning, Swiss, Welding · ISO 9001, AS9100, ISO 13485 | Sanford, NC | MillingTurningSwissWelding | ISO 9001, AS9100, ISO 13485 |
| JMG Tool LLC Milling, Turning, Laser, Welding, Finishing · ISO 9001, AS9100, ITAR | Loxahatchee, FL | MillingTurningLaserWeldingFinishing | ISO 9001, AS9100, ITAR |
| John J Steuby Co Milling, Turning, Swiss, Welding, Stamping, Casting, EDM, Finishing · ISO 9001, ITAR | Hazelwood, MO | MillingTurningSwissWeldingStampingCastingEDMFinishing | ISO 9001, ITAR |
| Johnson Manufacturing Systems LLC Milling, Turning, Welding, Grinding | Miamisburg, OH | MillingTurningWeldingGrinding | - |
| Joined Alloys Welding, EDM, Assembly · ISO 9001, NADCAP | Phoenix, AZ | WeldingEDMAssembly | ISO 9001, NADCAP |
| Jones & Lockhart Fabrication LLC Bending, Welding | St. Louis, MO | BendingWelding | - |
| Jones Co Machining Milling, Turning, Welding, Assembly | Hannibal, MO | MillingTurningWeldingAssembly | - |