| Smith Brothers Tool Company Milling, Welding · ISO 9001, AS9100, ITAR | Shelby Township, MI | MillingWelding | ISO 9001, AS9100, ITAR |
| Smith Metal, LLC Milling, Turning, Swiss, Laser, Waterjet, Bending, Welding, EDM, Grinding, Finishing · ISO 9001 | Augusta, MI | MillingTurningSwissLaserWaterjetBendingWeldingEDMGrindingFinishing | ISO 9001 |
| Smtautomation LLC Milling, Laser, Welding · ISO 9001, ITAR | Bruce Township, MI | MillingLaserWelding | ISO 9001, ITAR |
| Snoe, Inc. Machining & Welding Milling, Turning, Welding · ISO 9001 | Caldwell, TX | MillingTurningWelding | ISO 9001 |
| Soflo Machining Milling, Turning, Laser, Waterjet, Welding, Grinding, Finishing · ISO 9001, AS9100 | Coral Springs, FL | MillingTurningLaserWaterjetWeldingGrindingFinishing | ISO 9001, AS9100 |
| Sonoma Industries Inc Milling, Turning, Swiss · ISO 9001, AS9100, ITAR | Bell Gardens, CA | MillingTurningSwiss | ISO 9001, AS9100, ITAR |
| South Bend Form Tool Co Milling, Turning, EDM | South Bend, IN | MillingTurningEDM | - |
| Southeastern Machine Works, Inc Milling, Turning, Welding | Live Oak, FL | MillingTurningWelding | - |
| Southwest Greene International Inc Milling, Turning, Stamping, Metal AM, EDM | Oceanside, CA | MillingTurningStampingMetal AMEDM | - |
| Southwest Waterjet and Laser Milling, Laser, Waterjet, Bending | Phoenix, AZ | MillingLaserWaterjetBending | - |
| Spartan Machine LLC Milling, Turning | Spring, TX | MillingTurning | - |
| Sparton Technology Corp Milling, Turning, Laser, Punching, Bending, Welding, Finishing, Assembly · ISO 9001, AS9100 | Hudson, NH | MillingTurningLaserPunchingBendingWeldingFinishingAssembly | ISO 9001, AS9100 |
| Specialty Machine Milling, Turning, Swiss, Laser, Bending, Welding, EDM, Grinding, Assembly · ISO 9001, AS9100, ITAR | Lago Vista, TX | MillingTurningSwissLaserBendingWeldingEDMGrindingAssembly | ISO 9001, AS9100, ITAR |
| Specialty Precision Machining Milling, Turning, Laser · ISO 9001 | Stockton, CA | MillingTurningLaser | ISO 9001 |
| Spectrum Custom Molds & Manufacturing, Inc Milling, Turning, Laser, Welding, EDM, Grinding, Finishing, Assembly · ISO 9001 | Palmetto, FL | MillingTurningLaserWeldingEDMGrindingFinishingAssembly | ISO 9001 |
| Spring Creek Machining, Inc Milling, Turning, Waterjet, Bending, Welding, EDM, Grinding, Finishing | Lowell, AR | MillingTurningWaterjetBendingWeldingEDMGrindingFinishing | - |
| Srpm Inc Milling, Turning, Assembly · ISO 9001, ITAR | Solon, OH | MillingTurningAssembly | ISO 9001, ITAR |
| Stampede Die Corp Milling, Turning, Waterjet, Welding, Casting, EDM | Wayland, MI | MillingTurningWaterjetWeldingCastingEDM | - |
| Stanley Machining & Tool Corp Milling, Turning · ISO 9001 | Carpentersville, IL | MillingTurning | ISO 9001 |
| Starke Machine Co Milling, Turning · ISO 9001, AS9100, ITAR | Fort Worth, TX | MillingTurning | ISO 9001, AS9100, ITAR |
| Starlite Diversified Inc Milling, Turning, Welding, EDM, Grinding | Meadville, PA | MillingTurningWeldingEDMGrinding | - |
| Starn Tool & Manufacturing Company Milling, Turning, EDM, Grinding, Finishing · ISO 9001, ITAR | Meadville, PA | MillingTurningEDMGrindingFinishing | ISO 9001, ITAR |
| Steadfast Machine Milling, Turning · AS9100, ITAR | Bixby, OK | MillingTurning | AS9100, ITAR |
| Steelhead Metal Corp Milling, Turning, Laser, Waterjet, Bending, EDM, Finishing · ISO 9001 | Nampa, ID | MillingTurningLaserWaterjetBendingEDMFinishing | ISO 9001 |
| Stellar Engineering Milling, Turning · AS9100 | Anaheim, CA | MillingTurning | AS9100 |
| Stephens Precision, Inc Milling, Turning, Welding, EDM, Grinding, Assembly · ISO 9001, AS9100, ITAR | Bradford, VT | MillingTurningWeldingEDMGrindingAssembly | ISO 9001, AS9100, ITAR |
| Stork Precision Machining LLC Milling, Turning, Welding, EDM, Grinding · ISO 9001, CMMC | Washington, MO | MillingTurningWeldingEDMGrinding | ISO 9001, CMMC |
| Straton Industries Inc Milling, Turning, Stamping, EDM, Grinding, Finishing, Assembly · AS9100, ITAR, CMMC | Stratford, CT | MillingTurningStampingEDMGrindingFinishingAssembly | AS9100, ITAR, CMMC |
| Strickland Machine Co LLC Milling, Turning, Welding, Stamping, Grinding, Finishing, Assembly | North Chesterfield, VA | MillingTurningWeldingStampingGrindingFinishingAssembly | - |
| Strohwig Industries, Inc Milling, Turning, Casting, EDM, Grinding, Finishing, Assembly · ISO 9001, ITAR, CMMC | Richfield, WI | MillingTurningCastingEDMGrindingFinishingAssembly | ISO 9001, ITAR, CMMC |
| Subtract LLC Milling, Turning, Swiss, Laser, Waterjet, Welding, EDM, Finishing | Muncie, IN | MillingTurningSwissLaserWaterjetWeldingEDMFinishing | - |
| Summit Machine Company Milling, Turning, Welding, Finishing · ISO 9001 | Alverton, PA | MillingTurningWeldingFinishing | ISO 9001 |
| Summit Machining Co., Ltd Milling, Turning, Welding, Stamping, Casting, Finishing | Mogadore, OH | MillingTurningWeldingStampingCastingFinishing | - |
| Super Web Digital, Inc Milling, Turning, Welding, Grinding | West Babylon, NY | MillingTurningWeldingGrinding | - |
| Superior Jig Inc Milling, EDM · ISO 9001, ITAR | Anaheim, CA | MillingEDM | ISO 9001, ITAR |
| Superior Machining and Fabrication Inc Milling, Turning, Grinding, Assembly · ISO 9001, AS9100, ITAR | Muenster, TX | MillingTurningGrindingAssembly | ISO 9001, AS9100, ITAR |
| Superior Process Solutions Milling, Turning, Bending, Laser, Welding, Metal AM | Springfield, MO | MillingTurningBendingLaserWeldingMetal AM | - |
| Surfacemode, Inc Milling · ISO 9001, AS9100, ITAR | San Diego, CA | Milling | ISO 9001, AS9100, ITAR |
| Susquehanna Metal Work, LLC Milling, Bending, Welding, Stamping | Columbia, PA | MillingBendingWeldingStamping | - |
| Swiss-Tech LLC Milling, Turning, Swiss, Grinding, Finishing | Delavan, WI | MillingTurningSwissGrindingFinishing | - |
| Sync Milling | Purcellville, VA | Milling | - |
| T & D Specialties Milling, Turning, Swiss, Welding, Finishing · ISO 9001 | Oxford, MA | MillingTurningSwissWeldingFinishing | ISO 9001 |
| T.P. Engineering Inc Milling, Turning, Swiss, Welding, Grinding, Assembly · ISO 9001, ITAR, ISO 13485 | Danbury, CT | MillingTurningSwissWeldingGrindingAssembly | ISO 9001, ITAR, ISO 13485 |
| Tabet Manufacturing Co Inc Milling, Turning, Laser, Waterjet, Punching, Bending, Welding, Finishing, Assembly · ISO 9001, ITAR | Norfolk, VA | MillingTurningLaserWaterjetPunchingBendingWeldingFinishingAssembly | ISO 9001, ITAR |
| Tampa Bay Machining Milling, Turning, Welding, EDM · ISO 9001, AS9100, ITAR | Tampa, FL | MillingTurningWeldingEDM | ISO 9001, AS9100, ITAR |
| Tampa Brass and Aluminum Corporation Milling, Turning, Welding, Casting, Assembly | Tampa, FL | MillingTurningWeldingCastingAssembly | - |
| Tassell CNC Milling, Turning | Nunica, MI | MillingTurning | - |
| Taylor Turning Inc Milling, Turning, Grinding | Wixom, MI | MillingTurningGrinding | - |
| TCMS Inc Milling, Turning, Welding | Oklahoma City, OK | MillingTurningWelding | - |
| TDC Manufacturing Inc Milling, Turning, Laser | Redlands, CA | MillingTurningLaser | - |