| Oak Ridge Tool-Engineering Inc Milling, Turning, Welding, EDM, Grinding | Oak Ridge, TN | MillingTurningWeldingEDMGrinding | - |
| Oakes Manufacturing LLC Milling, Turning, Assembly · ISO 9001 | Fort Collins, CO | MillingTurningAssembly | ISO 9001 |
| Armec Corp Welding · ISO 9001 | Oak Ridge, TN | Welding | ISO 9001 |
| Charlie Mike Manufacturing LLC Milling, Turning, Laser, Bending, Welding, Stamping, EDM, Finishing | Oakdale, PA | MillingTurningLaserBendingWeldingStampingEDMFinishing | - |
| Demco Products Milling, Turning, Swiss, Finishing, Assembly · ISO 9001 | Oak Lawn, IL | MillingTurningSwissFinishingAssembly | ISO 9001 |
| Design Metal, Inc Milling, Turning, Bending, Welding, Stamping · ISO 9001 | Oak Park, MI | MillingTurningBendingWeldingStamping | ISO 9001 |
| Grain Valley Tool Manufacturing Welding · ISO 9001 | Oak Grove, MO | Welding | ISO 9001 |
| Harris Machine Co Milling, Bending, Welding, Finishing, Assembly | Oakes, ND | MillingBendingWeldingFinishingAssembly | - |
| Heighten America, Inc Milling, Turning, Welding, Assembly · ISO 9001 | Oakdale, CA | MillingTurningWeldingAssembly | ISO 9001 |
| Hennemuth Metal Fabricators Bending, Welding, Waterjet | Oakdale, PA | BendingWeldingWaterjet | - |
| Meyer Tool & Manufacturing, Inc Milling, Turning, Welding · ITAR | Oak Lawn, IL | MillingTurningWelding | ITAR |
| National Technologies, Inc Milling, Turning, Swiss, Grinding | Oak Creek, WI | MillingTurningSwissGrinding | - |
| Nuclear Lead Co, Inc Welding, Casting | Oak Ridge, TN | WeldingCasting | - |
| Owens Industries, Inc. Milling, Turning, Welding, EDM, Casting, Metal AM · ISO 9001, AS9100 | Oak Creek, WI | MillingTurningWeldingEDMCastingMetal AM | ISO 9001, AS9100 |
| Redwood Machine Works, Inc Waterjet, Welding · ISO 9001, AS9100 | Oakland, CA | WaterjetWelding | ISO 9001, AS9100 |
| Takfab Precision Gunsmithing LLC Milling, Welding | Oak Harbor, WA | MillingWelding | - |
| Tennessee Tool & Engineering Inc Welding, Casting, Assembly · ISO 9001 | Oak Ridge, TN | WeldingCastingAssembly | ISO 9001 |
| Total Machining USA Inc Bending, Welding · ISO 9001, AS9100, ITAR | Oakland Park, FL | BendingWelding | ISO 9001, AS9100, ITAR |
| Ultimate Manufacturing, Inc Milling, Turning, Grinding | Oakland Park, FL | MillingTurningGrinding | - |
| Weldway Steel Fabrication Inc Turning, Bending, Welding | Oakdale, CA | TurningBendingWelding | - |
| Southeastern Machine Works, Inc Milling, Turning, Welding | Live Oak, FL | MillingTurningWelding | - |