| Shape Shifters Inc Milling, Waterjet, Bending, Welding, Stamping, Finishing | Bloomfield, IN | MillingWaterjetBendingWeldingStampingFinishing | - |
| Sharp Dimension Inc Milling, Turning, Bending, Welding, Grinding, Finishing, Assembly · ISO 9001, ITAR | Fremont, CA | MillingTurningBendingWeldingGrindingFinishingAssembly | ISO 9001, ITAR |
| Sheet Metal Solutions Inc Welding, Finishing | Tangent, OR | WeldingFinishing | - |
| Sheetmetal Engineering Inc Milling, Laser, Punching, Bending, Welding · ISO 9001, AS9100 | Simi Valley, CA | MillingLaserPunchingBendingWelding | ISO 9001, AS9100 |
| Sick Fab LLC Milling, Bending, Welding | Las Vegas, NV | MillingBendingWelding | - |
| Silicon Valley Precision Inc Milling, Turning, Welding, Casting, Grinding, Finishing · ITAR | Livermore, CA | MillingTurningWeldingCastingGrindingFinishing | ITAR |
| Sinclair and Sons Custom Welding and Machining Service Inc Milling, Turning, Waterjet, Welding, Assembly · ISO 9001, AS9100, NADCAP | Wichita, KS | MillingTurningWaterjetWeldingAssembly | ISO 9001, AS9100, NADCAP |
| Skytop Machine and Tool, Inc Milling, Turning, Waterjet, Welding, Grinding | Port Matilda, PA | MillingTurningWaterjetWeldingGrinding | - |
| Slagel Manufacturing, Inc Bending, Welding, Finishing · ISO 9001 | Forrest, IL | BendingWeldingFinishing | ISO 9001 |
| Slim Haney Machining Inc Milling, Turning, Welding | Tulsa, OK | MillingTurningWelding | - |
| 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 |
| SMS Precision Tech, LLC Waterjet, Welding, EDM · ISO 9001 | Tomball, TX | WaterjetWeldingEDM | ISO 9001 |
| SMT Machine & Tool Milling, Turning, Welding, Casting | Green Bay, WI | MillingTurningWeldingCasting | - |
| 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 |
| Solvers Manufacturing Turning, Bending, Welding | Springfield, NE | TurningBendingWelding | - |
| Sound Manufacturing, Inc Milling, Laser, Punching, Bending, Welding, Assembly · ISO 9001 | Old Saybrook, CT | MillingLaserPunchingBendingWeldingAssembly | ISO 9001 |
| South Austin Metals Bending, Welding | Austin, TX | BendingWelding | - |
| Southeastern Machine Works, Inc Milling, Turning, Welding | Live Oak, FL | MillingTurningWelding | - |
| Southern Metal Fabricators, Inc Welding, Casting | Albertville, AL | WeldingCasting | - |
| Southern Rut Performance LLC Welding | Dahlonega, GA | Welding | - |
| Southwest Industrial Sales LLC Milling, Turning, Swiss, Bending, Welding, EDM, Assembly · ISO 9001, AS9100, ITAR, ISO 13485, CMMC | Chandler, AZ | MillingTurningSwissBendingWeldingEDMAssembly | ISO 9001, AS9100, ITAR, ISO 13485, CMMC |
| Southwest Precision Machining, L.L.C Milling, Turning, Swiss, Welding, Finishing | Tucson, AZ | MillingTurningSwissWeldingFinishing | - |
| SP Manufacturing Inc Milling, Turning, Welding, Finishing · ISO 9001, AS9100 | Livermore, CA | MillingTurningWeldingFinishing | ISO 9001, AS9100 |
| 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 Machining Inc Milling, Turning, Welding, Assembly · ISO 9001, ISO 13485 | Newberry, FL | MillingTurningWeldingAssembly | ISO 9001, ISO 13485 |
| Specialty Metal Fabricators Bending, Welding | Portland, OR | BendingWelding | - |
| Spectrum Custom Molds & Manufacturing, Inc Milling, Turning, Laser, Welding, EDM, Grinding, Finishing, Assembly · ISO 9001 | Palmetto, FL | MillingTurningLaserWeldingEDMGrindingFinishingAssembly | ISO 9001 |
| SpecWeld Milling, Welding, Assembly · ISO 9001 | Lake Orion, MI | MillingWeldingAssembly | ISO 9001 |
| SPM Milling, Turning, Welding, EDM, Grinding, Finishing, Assembly · ISO 9001 | Portland, OR | MillingTurningWeldingEDMGrindingFinishingAssembly | ISO 9001 |
| Spring Creek Machining, Inc Milling, Turning, Waterjet, Bending, Welding, EDM, Grinding, Finishing | Lowell, AR | MillingTurningWaterjetBendingWeldingEDMGrindingFinishing | - |
| Square Deal Machining Inc Milling, Turning, Laser, Bending, Welding, Grinding, Finishing, Assembly | Marathon, NY | MillingTurningLaserBendingWeldingGrindingFinishingAssembly | - |
| SRS Fabrication Inc. Milling, Turning, Bending, Welding, Waterjet | North Las Vegas, NV | MillingTurningBendingWeldingWaterjet | - |
| Sse Steel Fabrication Milling, Turning, Bending, Welding | Saint Bernard, LA | MillingTurningBendingWelding | - |
| Stampede Die Corp Milling, Turning, Waterjet, Welding, Casting, EDM | Wayland, MI | MillingTurningWaterjetWeldingCastingEDM | - |
| Stanfordville Machine & Manufacturing Co Inc Milling, Turning, Swiss, Welding, EDM, Grinding · ISO 9001, AS9100 | Poughkeepsie, NY | MillingTurningSwissWeldingEDMGrinding | ISO 9001, AS9100 |
| Stark Industrial, LLC Milling, Turning, Swiss, Welding, EDM, Grinding · ISO 9001 | North Canton, OH | MillingTurningSwissWeldingEDMGrinding | ISO 9001 |
| Starlite Diversified Inc Milling, Turning, Welding, EDM, Grinding | Meadville, PA | MillingTurningWeldingEDMGrinding | - |
| Steel Valley Fabricators, LLC Milling, Bending, Welding | Braddock, PA | MillingBendingWelding | - |
| Steelcrest Precision, Inc Milling, Turning, Swiss, Welding, EDM, Grinding, Assembly · ISO 9001, AS9100 | Wauseon, OH | MillingTurningSwissWeldingEDMGrindingAssembly | ISO 9001, AS9100 |
| Steelhead Composites, Inc Welding · ISO 9001, AS9100 | Golden, CO | Welding | ISO 9001, AS9100 |
| Steer Machine Tool and Die Corporation Milling, Turning, Welding, Grinding | Honesdale, PA | MillingTurningWeldingGrinding | - |
| Stephens Precision, Inc Milling, Turning, Welding, EDM, Grinding, Assembly · ISO 9001, AS9100, ITAR | Bradford, VT | MillingTurningWeldingEDMGrindingAssembly | ISO 9001, AS9100, ITAR |
| Stigtec Manufacturing Milling, Welding, EDM, Grinding, Finishing, Assembly | San Marcos, CA | MillingWeldingEDMGrindingFinishingAssembly | - |
| Streich Bros Inc Milling, Welding | Tacoma, WA | MillingWelding | - |
| Strickland Industries Milling, Turning, Laser, Bending, Welding, Assembly | Mansfield, TX | MillingTurningLaserBendingWeldingAssembly | - |
| Strickland Machine Co LLC Milling, Turning, Welding, Stamping, Grinding, Finishing, Assembly | North Chesterfield, VA | MillingTurningWeldingStampingGrindingFinishingAssembly | - |
| Striking Precision Welding & Fabrication Milling, Bending, Welding · ISO 9001, ITAR | Cedar Park, TX | MillingBendingWelding | ISO 9001, ITAR |