| D & D Automation Inc Milling, Turning, Welding, EDM | Terre Haute, IN | MillingTurningWeldingEDM | - |
| D & D Design & Manufacturing Inc Milling, Turning, Bending, Laser, Welding | Oklahoma City, OK | MillingTurningBendingLaserWelding | - |
| D & G Machine Products, LLC Milling, Turning, Bending, Laser, Welding · ISO 9001, AS9100 | Gorham, ME | MillingTurningBendingLaserWelding | ISO 9001, AS9100 |
| D & H Industries Inc Milling, Turning, Laser, Bending, Welding, Stamping, Grinding, Finishing · ISO 9001, ITAR | Oconomowoc, WI | MillingTurningLaserBendingWeldingStampingGrindingFinishing | ISO 9001, ITAR |
| D & S Machine Service Inc Milling, Turning, Welding · ISO 9001 | Luxemburg, WI | MillingTurningWelding | ISO 9001 |
| Dahlgren Technologies LLC Welding | King George, VA | Welding | - |
| Dallas Machine and Tool Milling, Welding | Carrollton, TX | MillingWelding | - |
| Dallas Precision Machining Milling, Turning, Bending, Laser, Welding, Waterjet, Metal AM · ISO 9001, AS9100, ITAR | Carrollton, TX | MillingTurningBendingLaserWeldingWaterjetMetal AM | ISO 9001, AS9100, ITAR |
| Dan's Custom Machining LLC Milling, Turning, Welding | Williamsburg, OH | MillingTurningWelding | - |
| Danco Precision, Inc Milling, Turning, Laser, Welding, Stamping, EDM, Grinding, Assembly · ISO 9001, AS9100, ITAR | Phoenixville, PA | MillingTurningLaserWeldingStampingEDMGrindingAssembly | ISO 9001, AS9100, ITAR |
| Danser, Inc Milling, Laser, Punching, Bending, Welding | Davisville, WV | MillingLaserPunchingBendingWelding | - |
| Dark Threat Fabrication LLC Milling, Turning, Laser, Bending, Welding, Finishing · ISO 9001 | Heber Springs, AR | MillingTurningLaserBendingWeldingFinishing | ISO 9001 |
| Davis Machine Works of Opelika Inc Welding | Opelika, AL | Welding | - |
| Davis Manufacturing Co Milling, Turning, Welding, Finishing · AS9100, ITAR, CMMC | Wheat Ridge, CO | MillingTurningWeldingFinishing | AS9100, ITAR, CMMC |
| Davis Tool & Die, Inc Milling, Turning, Welding, Stamping, EDM, Grinding | Abbeville, MS | MillingTurningWeldingStampingEDMGrinding | - |
| Davlan Engineering Inc Milling, Turning, Laser, Welding, Stamping | Saint Louis, MO | MillingTurningLaserWeldingStamping | - |
| Dearborn Bortec LLC Milling, Turning, Waterjet, Welding, EDM, Grinding, Finishing · ISO 9001, AS9100, ITAR | Fryeburg, ME | MillingTurningWaterjetWeldingEDMGrindingFinishing | ISO 9001, AS9100, ITAR |
| Decotron Welding, Metal AM | Dallas, TX | WeldingMetal AM | - |
| Defelice Engineering, Inc Milling, Turning, Bending, Welding, Casting, Grinding | Mooresville, IN | MillingTurningBendingWeldingCastingGrinding | - |
| Dellinger Enterprises, Ltd Milling, Turning, Laser, Bending, Welding, Stamping, Finishing | Belmont, NC | MillingTurningLaserBendingWeldingStampingFinishing | - |
| Delta Machine Company, LLC Milling, Turning, Welding, Grinding | Harbor City, CA | MillingTurningWeldingGrinding | - |
| Delta One Manufacturing LLC Milling, Turning, Laser, Welding, Finishing, Assembly | San Jose, CA | MillingTurningLaserWeldingFinishingAssembly | - |
| Deltisan Engineering LLC Milling, Turning, Punching, Bending, Welding, Finishing, Assembly · ISO 9001 | Parker, CO | MillingTurningPunchingBendingWeldingFinishingAssembly | ISO 9001 |
| Denali MetalWorks Bending, Laser, Welding, Waterjet | Phoenix, AZ | BendingLaserWeldingWaterjet | - |
| Denver Machine Shop Milling, Turning, Welding · ISO 9001 | Henderson, CO | MillingTurningWelding | ISO 9001 |
| Deperini Metal Fabricators Milling, Laser, Punching, Bending, Welding, Grinding, Finishing · ISO 9001 | Gaithersburg, MD | MillingLaserPunchingBendingWeldingGrindingFinishing | ISO 9001 |
| Derecktor Marine Technology LLC Milling, Turning, Waterjet, Welding | Bristol, RI | MillingTurningWaterjetWelding | - |
| Des Moines Iron & Supply Co Bending, Welding | Des Moines, IA | BendingWelding | - |
| Desert Precision Manufacturing Bending, Laser, Welding · ISO 9001 | Tucson, AZ | BendingLaserWelding | ISO 9001 |
| Design Metal, Inc Milling, Turning, Bending, Welding, Stamping · ISO 9001 | Oak Park, MI | MillingTurningBendingWeldingStamping | ISO 9001 |
| Designed With Sparks LLC Welding | Usk, WA | Welding | - |
| DGF Industrial Innovations Group, Ltd Milling, Turning, Bending, Welding · ISO 9001 | Gilford, NH | MillingTurningBendingWelding | ISO 9001 |
| Diamond Manufacturing of Bluffton, Ltd Laser, Welding, Assembly | Bluffton, OH | LaserWeldingAssembly | - |
| Diamond W Custom Machine Works LLC Milling, Turning, Laser, Waterjet, Welding, Finishing | Phillipsburg, KS | MillingTurningLaserWaterjetWeldingFinishing | - |
| Dicostanzo Welding Services LLC Welding | Anderson, SC | Welding | - |
| Die-Mension Corp Milling, Turning, Welding, Stamping, EDM, Grinding | Brunswick, OH | MillingTurningWeldingStampingEDMGrinding | - |
| Digital Machining Systems LLC Milling, Turning, Welding, Assembly · ISO 9001 | Duson, LA | MillingTurningWeldingAssembly | ISO 9001 |
| Dimark Precision Machining,, Inc Milling, Turning, Welding, Grinding | Pembroke, MA | MillingTurningWeldingGrinding | - |
| Direct Tooling Concepts LLP Welding, Stamping, EDM, Grinding | Versailles, OH | WeldingStampingEDMGrinding | - |
| Distinctive Machining LLC Milling, Welding, Grinding, Finishing | Zeeland, MI | MillingWeldingGrindingFinishing | - |
| Diversified Machining Inc Milling, Welding | Forest Hill, MD | MillingWelding | - |
| Dixon Tool & Die Co Inc Milling, Turning, Waterjet, Welding, EDM, Grinding · ISO 9001, CMMC | Tyrone, PA | MillingTurningWaterjetWeldingEDMGrinding | ISO 9001, CMMC |
| DK Machining LLC Milling, Turning, Welding, Assembly · ISO 9001, ITAR | Molalla, OR | MillingTurningWeldingAssembly | ISO 9001, ITAR |
| Domaille Engineering, LLC Milling, Turning, Welding, EDM, Grinding, Assembly | Rochester, MN | MillingTurningWeldingEDMGrindingAssembly | - |
| Dominguez Sheet Metal Works, Inc Welding | El Paso, TX | Welding | - |
| Donahue Industries, Incorporated Milling, Turning, Swiss, Punching, Bending, Welding, Stamping, EDM, Grinding, Finishing | Shrewsbury, MA | MillingTurningSwissPunchingBendingWeldingStampingEDMGrindingFinishing | - |
| Donsco, Inc Milling, Welding, Casting | Wrightsville, PA | MillingWeldingCasting | - |
| Dothan Steel Fabricators, LLC Welding | Dothan, AL | Welding | - |
| Douglas Machine & Engineering Milling, Turning, Bending, Welding, EDM · ISO 9001, AS9100, ITAR, CMMC | Davenport, IA | MillingTurningBendingWeldingEDM | ISO 9001, AS9100, ITAR, CMMC |
| Draeving Machine Tool, Inc Milling, Turning, Welding, EDM | Beloit, WI | MillingTurningWeldingEDM | - |