| Salsa Prototype Specialties Milling, Turning, Waterjet · ISO 9001 | Ventura, CA | MillingTurningWaterjet | ISO 9001 |
| San Diego Precision Machining Inc Milling, Turning, Welding, EDM · ISO 9001, AS9100 | San Diego, CA | MillingTurningWeldingEDM | ISO 9001, AS9100 |
| San Jose Die Casting & Machining Corp Casting | Lincoln, CA | Casting | - |
| Sawyer Manufacturing Company Turning, Welding, Finishing | Tulsa, OK | TurningWeldingFinishing | - |
| Schred Machine Company, Inc Milling, Turning · AS9100 | Warminster, PA | MillingTurning | AS9100 |
| SendCutSend Milling, Bending, Laser, Welding, Waterjet | Reno, NV | MillingBendingLaserWeldingWaterjet | - |
| Sepco Erie Milling, Turning, Stamping · ISO 9001 | Erie, PA | MillingTurningStamping | ISO 9001 |
| Serrmi Products LLC Milling, Turning, Laser, Punching, Bending, Finishing | Pittsburg, KS | MillingTurningLaserPunchingBendingFinishing | - |
| Sicom Industries USA LLC Milling, Turning, Waterjet · ISO 9001, AS9100, CMMC | Stanwood, WA | MillingTurningWaterjet | ISO 9001, AS9100, CMMC |
| Skydrive LLC Milling · ISO 9001, AS9100, ITAR | Collierville, TN | Milling | ISO 9001, AS9100, ITAR |
| Solmet Technologies Inc Forging | Canton, OH | Forging | - |
| Solvers Manufacturing Turning, Bending, Welding | Springfield, NE | TurningBendingWelding | - |
| Sonic Aerospace Inc Milling, Turning, Grinding, Finishing, Assembly · ISO 9001, AS9100 | Chandler, AZ | MillingTurningGrindingFinishingAssembly | ISO 9001, AS9100 |
| Sonic Manufacturing Corporation Milling, Welding, EDM, Grinding, Finishing, Assembly · AS9100, NADCAP | Elk Grove Village, IL | MillingWeldingEDMGrindingFinishingAssembly | AS9100, NADCAP |
| South Austin Metals Bending, Welding | Austin, TX | BendingWelding | - |
| Southern Ohio Manufacturing Milling, Turning, Laser, Bending, Welding, Grinding, Finishing | Amelia, OH | MillingTurningLaserBendingWeldingGrindingFinishing | - |
| Southern Precision, Inc Milling, Turning, Stamping | Saint Rose, LA | MillingTurningStamping | - |
| Specialty Engineering Inc Laser, Punching, Bending, Welding, Assembly · ISO 9001 | Saint Paul, MN | LaserPunchingBendingWeldingAssembly | ISO 9001 |
| Speed Fabrication LLC Laser, Bending, Welding, Finishing | Perryville, MO | LaserBendingWeldingFinishing | - |
| SPM Milling, Turning, Welding, EDM, Grinding, Finishing, Assembly · ISO 9001 | Portland, OR | MillingTurningWeldingEDMGrindingFinishingAssembly | ISO 9001 |
| Statt Engineering LLC Milling, Stamping · AS9100, ITAR | Martinsville, IN | MillingStamping | AS9100, ITAR |
| Steel House Bending, Welding | Indianapolis, IN | BendingWelding | - |
| Steel Tech Fabricator Welding | Rochester, NY | Welding | - |
| Stigtec Manufacturing Milling, Welding, EDM, Grinding, Finishing, Assembly | San Marcos, CA | MillingWeldingEDMGrindingFinishingAssembly | - |
| Streamline Tool & Engineering LLC Swiss | Peculiar, MO | Swiss | - |
| Strong Forge & Fabrication, LLC Milling, Bending, Welding, Finishing | Batavia, NY | MillingBendingWeldingFinishing | - |
| Sturdy Grinding & Machining Inc Grinding, Finishing · ISO 9001 | New Haven, MI | GrindingFinishing | ISO 9001 |
| Summit Machine Company Milling, Turning, Welding, Finishing · ISO 9001 | Alverton, PA | MillingTurningWeldingFinishing | ISO 9001 |
| Suntiger Industries LLC Welding · ISO 9001, AS9100, ITAR | Oceanside, CA | Welding | ISO 9001, AS9100, ITAR |
| Swift Industries Inc Milling, Laser, Punching, Bending, Welding, Stamping, Grinding, Finishing, Assembly · ISO 9001 | Suwanee, GA | MillingLaserPunchingBendingWeldingStampingGrindingFinishingAssembly | ISO 9001 |
| Swiss Productions, Inc Milling, Turning, Assembly · ISO 9001 | Liberty Lake, WA | MillingTurningAssembly | ISO 9001 |
| Sylhan LLC Milling, Turning, EDM · AS9100 | Edgewood, NY | MillingTurningEDM | AS9100 |
| Tampa Bay Machining Milling, Turning, Welding, EDM · ISO 9001, AS9100, ITAR | Tampa, FL | MillingTurningWeldingEDM | ISO 9001, AS9100, ITAR |
| TDC Manufacturing Inc Milling, Turning, Laser | Redlands, CA | MillingTurningLaser | - |
| Tec Inc Milling, Turning, Swiss, Laser, Punching, Bending, Welding, Finishing, Assembly · ISO 9001 | Frederick, MD | MillingTurningSwissLaserPunchingBendingWeldingFinishingAssembly | ISO 9001 |
| Tech Five Machining LLC Milling, Turning, Finishing · ISO 9001, AS9100, ITAR | Tempe, AZ | MillingTurningFinishing | ISO 9001, AS9100, ITAR |
| Techcraft Precision Milling, Finishing · AS9100, ITAR, CMMC | Bellingham, WA | MillingFinishing | AS9100, ITAR, CMMC |
| Texas Metal Specialty Co Laser, Welding, Waterjet | Houston, TX | LaserWeldingWaterjet | - |
| Texas Specialty Steel Welding | San Antonio, TX | Welding | - |
| The Trico Machine Products Corp Milling, Turning, Bending | Cleveland, OH | MillingTurningBending | - |
| Theonics Milling, Turning, Bending, Welding, EDM · AS9100, ITAR, ISO 13485 | Huntsville, AL | MillingTurningBendingWeldingEDM | AS9100, ITAR, ISO 13485 |
| Timber Mountain Precision Inc Milling · ISO 9001, AS9100 | Queen Creek, AZ | Milling | ISO 9001, AS9100 |
| Tinker Manufacturing Milling · ISO 9001, ITAR | Bedford, NH | Milling | ISO 9001, ITAR |
| Top Notch Machining, Inc Milling, Waterjet, Stamping, Finishing, Assembly · ISO 9001 | Gresham, OR | MillingWaterjetStampingFinishingAssembly | ISO 9001 |
| Toth Industries Inc Milling, Turning, Bending, Casting · ISO 9001 | Toledo, OH | MillingTurningBendingCasting | ISO 9001 |
| Touchdown Machining Inc Milling, Turning | Columbus, IN | MillingTurning | - |
| Tozli Machine Milling, Welding, Finishing · ISO 9001, ITAR, CMMC | Surprise, AZ | MillingWeldingFinishing | ISO 9001, ITAR, CMMC |
| Trace Technologies, LLC Milling, Finishing | Epping, NH | MillingFinishing | - |
| Tram-Tek, Inc Milling, Turning, EDM, Grinding · ISO 9001, AS9100 | Phoenix, AZ | MillingTurningEDMGrinding | ISO 9001, AS9100 |
| Tri Angle Metal Fab Milling, Turning, Laser, Punching, Bending, Welding, EDM, Grinding, Assembly · NADCAP | Milton, VT | MillingTurningLaserPunchingBendingWeldingEDMGrindingAssembly | NADCAP |