| Ability Metal Company Milling, Turning, Assembly | Elk Grove Village, IL | MillingTurningAssembly | - |
| R. A. Zweig, Inc Milling, Swiss, Finishing, Assembly | Glenview, IL | MillingSwissFinishingAssembly | - |
| Atlas Tool & Die Works Inc Turning, Laser, Waterjet, Welding, Stamping, EDM, Assembly | Lyons, IL | TurningLaserWaterjetWeldingStampingEDMAssembly | - |
| Bland Brothers Enterprises Milling, Welding, Assembly | Springfield, IL | MillingWeldingAssembly | - |
| Burns Machine Co Milling, Turning, Bending, Welding, Grinding, Assembly · ISO 9001 | Ottawa, IL | MillingTurningBendingWeldingGrindingAssembly | ISO 9001 |
| Clinkenbeard & Associates Inc Milling, Casting, Assembly · AS9100, ITAR | South Beloit, IL | MillingCastingAssembly | AS9100, ITAR |
| Cornell Forge Company Welding, Forging, Finishing, Assembly · ISO 9001, AS9100, NADCAP | Chicago, IL | WeldingForgingFinishingAssembly | ISO 9001, AS9100, NADCAP |
| Frey & Weiss Precision Machining Inc Milling, Turning, Grinding, Assembly · ISO 9001 | Wood Dale, IL | MillingTurningGrindingAssembly | ISO 9001 |
| LZ Machine LLC Milling, Turning, Assembly | Eureka, IL | MillingTurningAssembly | - |
| Prototype & Production Co., Inc Milling, Turning, EDM, Grinding, Assembly · ISO 9001, ITAR | Wheeling, IL | MillingTurningEDMGrindingAssembly | ISO 9001, ITAR |
| Sugar River Machine Inc Milling, Turning, Welding, Grinding, Finishing, Assembly | South Beloit, IL | MillingTurningWeldingGrindingFinishingAssembly | - |
| Systems Powered Manufacturing, LLC Grinding, Finishing, Assembly | Saint Charles, IL | GrindingFinishingAssembly | - |