| OMS Precision Machining Milling, Turning, Swiss, Casting, Grinding, Finishing · ISO 9001, ITAR | Oshkosh, WI | MillingTurningSwissCastingGrindingFinishing | ISO 9001, ITAR |
| Orlando Metal Fabrication Inc Milling, Waterjet, Punching, Bending, Welding, Finishing · ISO 9001, AS9100 | Orlando, FL | MillingWaterjetPunchingBendingWeldingFinishing | ISO 9001, AS9100 |
| Operateup Inc Milling, Turning, Punching, Welding, Stamping · ISO 9001 | Orange, MA | MillingTurningPunchingWeldingStamping | ISO 9001 |
| Owens Industries, Inc. Milling, Turning, Welding, EDM, Casting, Metal AM · ISO 9001, AS9100 | Oak Creek, WI | MillingTurningWeldingEDMCastingMetal AM | ISO 9001, AS9100 |
| David Packard Company, Inc Milling, Turning, Swiss, Grinding, Finishing, Assembly · ISO 9001, ITAR | Oxford, MA | MillingTurningSwissGrindingFinishingAssembly | ISO 9001, ITAR |
| Demco Products Milling, Turning, Swiss, Finishing, Assembly · ISO 9001 | Oak Lawn, IL | MillingTurningSwissFinishingAssembly | ISO 9001 |
| Fox Worx Precision LLC Milling, Finishing · ISO 9001, ITAR | Ontario, OR | MillingFinishing | ISO 9001, ITAR |
| General Plug and Manufacturing Co Milling, Casting, EDM, Grinding, Finishing · ISO 9001 | Oberlin, OH | MillingCastingEDMGrindingFinishing | ISO 9001 |
| KW Products, Inc Milling, Turning, Finishing · ISO 9001, AS9100 | Oldsmar, FL | MillingTurningFinishing | ISO 9001, AS9100 |
| MMG Corp Milling, Turning, Finishing, Assembly · ISO 9001 | Ontario, CA | MillingTurningFinishingAssembly | ISO 9001 |
| Aero Components Inc Milling, Turning, EDM, Grinding · ISO 9001 | Oklahoma City, OK | MillingTurningEDMGrinding | ISO 9001 |
| Aerotar Inc Milling, Welding, Grinding · ISO 9001 | Opa Locka, FL | MillingWeldingGrinding | ISO 9001 |
| Anaheim Precision Milling, Turning, Bending, Laser, Welding, Waterjet · ISO 9001, AS9100, NADCAP | Orange, CA | MillingTurningBendingLaserWeldingWaterjet | ISO 9001, AS9100, NADCAP |
| Angeles Precision Engineering LLC Milling, Turning, Assembly · ISO 9001, ITAR | Ontario, CA | MillingTurningAssembly | ISO 9001, ITAR |
| Burns Machine Co Milling, Turning, Bending, Welding, Grinding, Assembly · ISO 9001 | Ottawa, IL | MillingTurningBendingWeldingGrindingAssembly | ISO 9001 |
| Ems Automotive Milling, Turning, Welding, Grinding · ISO 9001, ITAR | Orange, CA | MillingTurningWeldingGrinding | ISO 9001, ITAR |
| Farrar Aerospace LLC Milling, Turning · ISO 9001, ITAR | Ontario, CA | MillingTurning | ISO 9001, ITAR |
| JW Machine (Praesto Enterprises, LLC) Milling, Turning, Laser · ISO 9001, AS9100, ITAR | Orlando, FL | MillingTurningLaser | ISO 9001, AS9100, ITAR |
| Nelgo Manufacturing Co Milling, Turning, Punching, Welding · ISO 9001, AS9100, ITAR | Oceanside, CA | MillingTurningPunchingWelding | ISO 9001, AS9100, ITAR |
| Planet Tool & Gear Inc Milling, Welding, Stamping, Assembly · ISO 9001, AS9100, ITAR | O Fallon, MO | MillingWeldingStampingAssembly | ISO 9001, AS9100, ITAR |
| Precision CNC Machining Milling, Turning · ISO 9001 | Oxnard, CA | MillingTurning | ISO 9001 |
| Quick Turn Precision Machining Milling, Turning, Welding · ISO 9001 | Ogden, UT | MillingTurningWelding | ISO 9001 |
| R & G Precision Machining Inc Milling, Turning · ISO 9001, AS9100 | Oceanside, CA | MillingTurning | ISO 9001, AS9100 |
| Sharp Tool Manufacturing Milling, Turning, Welding · ISO 9001, AS9100, ITAR, CMMC | Ogden, UT | MillingTurningWelding | ISO 9001, AS9100, ITAR, CMMC |
| Sound Manufacturing, Inc Milling, Laser, Punching, Bending, Welding, Assembly · ISO 9001 | Old Saybrook, CT | MillingLaserPunchingBendingWeldingAssembly | ISO 9001 |
| Tri-V Tool & Manufacturing Co Milling, Turning, Bending, Welding, Waterjet, EDM · ISO 9001 | Omaha, NE | MillingTurningBendingWeldingWaterjetEDM | ISO 9001 |
| Marion Precision Tool, Inc Milling, Turning, Waterjet, Bending, Welding, Grinding · ISO 9001 | Ocala, FL | MillingTurningWaterjetBendingWeldingGrinding | ISO 9001 |
| Oak Ridge Tool-Engineering Inc Milling, Turning, Welding, EDM, Grinding | Oak Ridge, TN | MillingTurningWeldingEDMGrinding | - |
| Ankeny Automation, LLC Milling, Laser, Welding, Grinding, Finishing | Omaha, NE | MillingLaserWeldingGrindingFinishing | - |
| Austin Machine Co Milling, Turning, Waterjet · ISO 9001 | O Fallon, MO | MillingTurningWaterjet | ISO 9001 |
| Critical Components-Oil & Gas Milling, Turning, Welding, Metal AM, Finishing | Oklahoma City, OK | MillingTurningWeldingMetal AMFinishing | - |
| Harris Machine Co Milling, Bending, Welding, Finishing, Assembly | Oakes, ND | MillingBendingWeldingFinishingAssembly | - |
| Korzan Enterprises Inc Milling, Turning, Waterjet, Welding, EDM, Grinding, Finishing | Orchard Park, NY | MillingTurningWaterjetWeldingEDMGrindingFinishing | - |
| NTO Designs Milling, Turning, Laser, Welding, Finishing | Ormond Beach, FL | MillingTurningLaserWeldingFinishing | - |
| Odyssey Machining Milling, Finishing · ISO 9001, ITAR | San Jose, CA | MillingFinishing | ISO 9001, ITAR |
| Omanson Precision Engineering, Inc Milling, Finishing · ISO 9001, AS9100 | Chino, CA | MillingFinishing | ISO 9001, AS9100 |
| Omni Precision Components Milling, Turning, Finishing · ISO 9001 | Holland, MI | MillingTurningFinishing | ISO 9001 |
| One Source Manufacturing Technology LLC Milling, Turning, Welding, Grinding, Finishing · ISO 9001, AS9100 | Leander, TX | MillingTurningWeldingGrindingFinishing | ISO 9001, AS9100 |
| Ortiz Tool, LLC Milling, Turning, Finishing, Assembly · ISO 9001, AS9100, ITAR, NADCAP | Windsor, CT | MillingTurningFinishingAssembly | ISO 9001, AS9100, ITAR, NADCAP |
| Precisioncore Manufacturing LLC Milling, Laser, Bending, Finishing · CMMC | Orange City, FL | MillingLaserBendingFinishing | CMMC |
| Acc Precision Inc Milling, Turning, Welding, Grinding | Oxnard, CA | MillingTurningWeldingGrinding | - |
| Advanced Machining Solutions Milling, Turning, Welding | Oklahoma City, OK | MillingTurningWelding | - |
| Albert Precision Machining Milling, Turning, Grinding | Omaha, NE | MillingTurningGrinding | - |
| American Machining Inc Milling, Turning, Welding, Grinding, Finishing · ISO 9001 | Ottawa, IL | MillingTurningWeldingGrindingFinishing | ISO 9001 |
| Apex Precision CNC Milling, Turning, Punching, Bending, Stamping, Casting, EDM, Grinding, Assembly · ITAR, CMMC | Orem, UT | MillingTurningPunchingBendingStampingCastingEDMGrindingAssembly | ITAR, CMMC |
| BMW Precision Machining Milling, Turning, Swiss · ITAR | Oceanside, CA | MillingTurningSwiss | ITAR |
| Casemer Tool & Machine Inc Milling, Turning, Laser, Waterjet, Welding, EDM, Grinding | Oxford, MI | MillingTurningLaserWaterjetWeldingEDMGrinding | - |
| CNC Innotech LLC Milling, Turning, Swiss | Ogdensburg, NJ | MillingTurningSwiss | - |
| D & H Industries Inc Milling, Turning, Laser, Bending, Welding, Stamping, Grinding, Finishing · ISO 9001, ITAR | Oconomowoc, WI | MillingTurningLaserBendingWeldingStampingGrindingFinishing | ISO 9001, ITAR |
| Elemetal Fabrication and Machine (Formerly American Machine Works) Milling, Bending, Welding, Waterjet | Omaha, NE | MillingBendingWeldingWaterjet | - |