| Cat-Wood Metalworks Milling, Turning, Assembly · ISO 9001, ITAR | Moraine, OH | MillingTurningAssembly | ISO 9001, ITAR |
| CB Manufacturing & Engineering Inc Milling, Turning, EDM · ISO 9001, AS9100 | Santa Ana, CA | MillingTurningEDM | ISO 9001, AS9100 |
| Center Machine Inc Milling, Turning, Bending, Welding | Center, ND | MillingTurningBendingWelding | - |
| Centerline Engineered Solutions, Inc Milling, Turning, Laser, Bending, Welding · ISO 9001 | Greenwood, SC | MillingTurningLaserBendingWelding | ISO 9001 |
| Centerline Machine, LLC Milling, Turning, Waterjet, Bending, Welding, Finishing, Assembly · ISO 9001, ITAR | Waupaca, WI | MillingTurningWaterjetBendingWeldingFinishingAssembly | ISO 9001, ITAR |
| Chesapeake Machine Co Milling, Welding | Baltimore, MD | MillingWelding | - |
| Clark Metal Products Co Milling, Laser, Punching, Bending, Welding, Finishing, Assembly · ISO 9001 | Blairsville, PA | MillingLaserPunchingBendingWeldingFinishingAssembly | ISO 9001 |
| Clow Stamping Company, Inc Milling, Turning, Laser, Bending, Welding, Stamping, EDM, Grinding, Finishing, Assembly | Merrifield, MN | MillingTurningLaserBendingWeldingStampingEDMGrindingFinishingAssembly | - |
| Coanda Company LLC, the Milling, Turning, Waterjet, Welding · ISO 9001, AS9100 | Shawnee, OK | MillingTurningWaterjetWelding | ISO 9001, AS9100 |
| Coast Aerospace Manufacturing, Inc Milling, Welding · AS9100, ITAR | Placentia, CA | MillingWelding | AS9100, ITAR |
| Colburn Manufacturing Company Milling, Turning · ISO 9001, ISO 13485 | Fridley, MN | MillingTurning | ISO 9001, ISO 13485 |
| Collins Manufacturing Inc Milling, Turning, EDM · ITAR | Essex, MA | MillingTurningEDM | ITAR |
| Computer Components Corporation Milling, Turning, Punching, Bending, Welding, Assembly · ISO 9001, ITAR | Philadelphia, PA | MillingTurningPunchingBendingWeldingAssembly | ISO 9001, ITAR |
| Concise Manufacturing Inc Milling, Turning, Welding, EDM | Salisbury, NC | MillingTurningWeldingEDM | - |
| Conner Brothers Machine Co., Inc Milling, Turning, Welding, Grinding · ISO 9001 | Bessemer City, NC | MillingTurningWeldingGrinding | ISO 9001 |
| Contract Machining Milling, Turning, Welding · ISO 9001 | Lexington, KY | MillingTurningWelding | ISO 9001 |
| Cortec Precision Sheetmetal Milling, Turning, Bending, Laser, Welding | San Jose, CA | MillingTurningBendingLaserWelding | - |
| Creative CNC LLC Milling | New Berlin, WI | Milling | - |
| Critical Defense Inc Milling, Turning, Bending, Welding, Grinding, Assembly | Windber, PA | MillingTurningBendingWeldingGrindingAssembly | - |
| Crystal Engineering Co., Inc Milling, Stamping | Newburyport, MA | MillingStamping | - |
| Cuddeback Machining, Inc Milling, Turning, Laser, Welding, Stamping, EDM, Grinding · ISO 9001 | Hilton, NY | MillingTurningLaserWeldingStampingEDMGrinding | ISO 9001 |
| Custom Engineering Co Milling, Turning, Bending, Welding · ISO 9001, ITAR, NADCAP | Erie, PA | MillingTurningBendingWelding | ISO 9001, ITAR, NADCAP |
| Custom Machine Milling, Turning, Welding, Grinding | Hagerstown, MD | MillingTurningWeldingGrinding | - |
| Custom Materials Inc Milling, Welding, Stamping, Grinding, Assembly · ISO 9001 | Chagrin Falls, OH | MillingWeldingStampingGrindingAssembly | ISO 9001 |
| Custom Metal Works Milling, Bending, Welding | Tulsa, OK | MillingBendingWelding | - |
| Custom Metalcraft Milling, Bending, Welding | Springfield, MO | MillingBendingWelding | - |
| Cutting Edge Manufacturing Milling, Turning, Assembly · ISO 9001, AS9100 | Newbury Park, CA | MillingTurningAssembly | ISO 9001, AS9100 |
| CV International, Inc Milling, Turning, Laser, Punching, Bending, Welding · ISO 9001 | Bend, OR | MillingTurningLaserPunchingBendingWelding | ISO 9001 |
| Cyclefab, LLC Milling, Turning, Welding | Renton, WA | MillingTurningWelding | - |
| D & D Manufacturing LLC Milling, Turning, Grinding | Ipswich, MA | MillingTurningGrinding | - |
| D & G Manufacturing LLC Milling, Turning, Welding | Aurora, CO | MillingTurningWelding | - |
| D & H Industries Inc Milling, Turning, Laser, Bending, Welding, Stamping, Grinding, Finishing · ISO 9001, ITAR | Oconomowoc, WI | MillingTurningLaserBendingWeldingStampingGrindingFinishing | ISO 9001, ITAR |
| D&D Enterprises of Greensboro Inc Milling, Turning, Swiss, Assembly · ISO 9001, AS9100 | Randleman, NC | MillingTurningSwissAssembly | ISO 9001, AS9100 |
| D&T Dynamics LLC Milling | Hyrum, UT | Milling | - |
| Dalton Manufacturing Group Inc Milling, Turning, Grinding · ISO 9001, CMMC | Amesbury, MA | MillingTurningGrinding | ISO 9001, CMMC |
| Damco, Inc Milling, Turning, Waterjet, Welding | New Bern, NC | MillingTurningWaterjetWelding | - |
| Danser, Inc Milling, Laser, Punching, Bending, Welding | Davisville, WV | MillingLaserPunchingBendingWelding | - |
| Dawid Manufacturing Inc Milling, Welding | Ansonia, CT | MillingWelding | - |
| Decimal Engineering Milling, Turning, Laser, Stamping, EDM, Grinding, Finishing, Assembly · ISO 9001, AS9100, ITAR, NADCAP | Coral Springs, FL | MillingTurningLaserStampingEDMGrindingFinishingAssembly | ISO 9001, AS9100, ITAR, NADCAP |
| Decker Machine Works Inc Milling, Turning, Swiss, EDM, Grinding · ISO 9001, AS9100, ITAR | Greenfield, MA | MillingTurningSwissEDMGrinding | ISO 9001, AS9100, ITAR |
| Delta One Manufacturing LLC Milling, Turning, Laser, Welding, Finishing, Assembly | San Jose, CA | MillingTurningLaserWeldingFinishingAssembly | - |
| Delta V LLC Milling · ISO 9001 | Sanford, FL | Milling | ISO 9001 |
| Dessureau Machines Inc Milling, Turning, Welding | Berlin, VT | MillingTurningWelding | - |
| Die Craft Milling, Turning, Welding, Waterjet · ISO 9001 | Cincinnati, OH | MillingTurningWeldingWaterjet | ISO 9001 |
| Distinctive Machining LLC Milling, Welding, Grinding, Finishing | Zeeland, MI | MillingWeldingGrindingFinishing | - |
| Dms-South/bailey Tool LLC Milling, Turning, Welding, Stamping, EDM | Lancaster, TX | MillingTurningWeldingStampingEDM | - |
| Donsco, Inc Milling, Welding, Casting | Wrightsville, PA | MillingWeldingCasting | - |
| Draeving Machine Tool, Inc Milling, Turning, Welding, EDM | Beloit, WI | MillingTurningWeldingEDM | - |
| DRM Industries Corp Milling, Turning, Laser, Welding, Casting · ISO 9001 | Lake Delton, WI | MillingTurningLaserWeldingCasting | ISO 9001 |
| Dutchy Enterprises LLC Milling, Waterjet, Welding | Cocoa, FL | MillingWaterjetWelding | - |