| Jetfab LLC Milling, Turning, Laser, Waterjet, Punching, Bending, Welding | Lowell, MA | MillingTurningLaserWaterjetPunchingBendingWelding | - |
| JJR Engineering & Fabrication Inc Milling, Turning, Bending, Welding, Stamping, Finishing, Assembly · ISO 9001, AS9100, NADCAP | Woodinville, WA | MillingTurningBendingWeldingStampingFinishingAssembly | ISO 9001, AS9100, NADCAP |
| JMG Tool LLC Milling, Turning, Laser, Welding, Finishing · ISO 9001, AS9100, ITAR | Loxahatchee, FL | MillingTurningLaserWeldingFinishing | ISO 9001, AS9100, ITAR |
| JMR Machining LLC Milling, Turning, Casting, Finishing | Athens, TX | MillingTurningCastingFinishing | - |
| John J Steuby Co Milling, Turning, Swiss, Welding, Stamping, Casting, EDM, Finishing · ISO 9001, ITAR | Hazelwood, MO | MillingTurningSwissWeldingStampingCastingEDMFinishing | ISO 9001, ITAR |
| Jonesboro Tool & Die Co Inc Milling, Turning, Laser, Waterjet, Bending, Welding, Stamping, EDM, Grinding · AS9100, ITAR, CMMC | Jonesboro, AR | MillingTurningLaserWaterjetBendingWeldingStampingEDMGrinding | AS9100, ITAR, CMMC |
| JP Metal Fabrication, Inc. Milling, Bending, Laser, Welding | Santa Clara, CA | MillingBendingLaserWelding | - |
| JW Machine (Praesto Enterprises, LLC) Milling, Turning, Laser · ISO 9001, AS9100, ITAR | Orlando, FL | MillingTurningLaser | ISO 9001, AS9100, ITAR |
| K & B Machining Inc Milling, Turning, Laser, Grinding, Finishing · ISO 9001, ITAR | Claremore, OK | MillingTurningLaserGrindingFinishing | ISO 9001, ITAR |
| K&M Milling, Turning, Laser, Welding, Assembly · ISO 9001 | Cassopolis, MI | MillingTurningLaserWeldingAssembly | ISO 9001 |
| Kad Models and Prototypes Inc Milling, Finishing, Assembly | East Randolph, VT | MillingFinishingAssembly | - |
| Kaydek Machining, Inc Milling, Turning, Finishing · ISO 9001, AS9100 | San Jose, CA | MillingTurningFinishing | ISO 9001, AS9100 |
| Kennley Corp Milling, Turning, Grinding, Finishing | North Chesterfield, VA | MillingTurningGrindingFinishing | - |
| Kineo, Inc Milling, Turning, EDM, Grinding, Finishing · ISO 9001, ISO 13485 | Colorado Springs, CO | MillingTurningEDMGrindingFinishing | ISO 9001, ISO 13485 |
| Kinross Fab & Machine Inc Milling, Turning, Laser, Welding, Grinding, Finishing | Kincheloe, MI | MillingTurningLaserWeldingGrindingFinishing | - |
| Kinship Precision LLC Milling, Turning, Swiss, Laser · ISO 9001, ISO 13485 | Melbourne, FL | MillingTurningSwissLaser | ISO 9001, ISO 13485 |
| Kirsh Manufacturing Inc Milling, Turning, Welding, Grinding, Finishing · ISO 9001, ITAR | Tucson, AZ | MillingTurningWeldingGrindingFinishing | ISO 9001, ITAR |
| KLH Industries Inc Milling, Turning, Waterjet, Bending, Welding, EDM, Grinding, Finishing · ISO 9001, AS9100, ITAR, NADCAP | Germantown, WI | MillingTurningWaterjetBendingWeldingEDMGrindingFinishing | ISO 9001, AS9100, ITAR, NADCAP |
| KLM Machining, Inc Milling, Turning, Welding, Finishing | Sussex, WI | MillingTurningWeldingFinishing | - |
| Korzan Enterprises Inc Milling, Turning, Waterjet, Welding, EDM, Grinding, Finishing | Orchard Park, NY | MillingTurningWaterjetWeldingEDMGrindingFinishing | - |
| Kriewall Enterprises Inc Milling, Laser, Welding, Stamping, EDM, Finishing · ISO 9001 | Romeo, MI | MillingLaserWeldingStampingEDMFinishing | ISO 9001 |
| Kte Holdings LLC Milling, Turning, Welding, Grinding, Finishing | Mableton, GA | MillingTurningWeldingGrindingFinishing | - |
| KV Engineering LLC Milling, Turning, Laser, Waterjet, Welding | Miami, FL | MillingTurningLaserWaterjetWelding | - |
| KW Products, Inc Milling, Turning, Finishing · ISO 9001, AS9100 | Oldsmar, FL | MillingTurningFinishing | ISO 9001, AS9100 |
| LD Redmer Milling, Turning, Swiss, Welding, Finishing · ISO 9001, ITAR, NADCAP | Bensenville, IL | MillingTurningSwissWeldingFinishing | ISO 9001, ITAR, NADCAP |
| Lemmatic Precision LLC Milling, Turning, Finishing · ISO 9001, ITAR | American Fork, UT | MillingTurningFinishing | ISO 9001, ITAR |
| Lewis Precision & CNC Inc Milling, Turning, Bending, Welding, Grinding, Finishing · ISO 9001, AS9100 | Theodore, AL | MillingTurningBendingWeldingGrindingFinishing | ISO 9001, AS9100 |
| LG Metalworks LLC Milling, Turning, Laser, Waterjet, Welding, EDM, Finishing | Bloomington, IN | MillingTurningLaserWaterjetWeldingEDMFinishing | - |
| LHM Engineering LLC Milling, Swiss, Laser, Waterjet, Stamping, EDM, Grinding, Finishing, Assembly · ISO 13485 | Manchester, MA | MillingSwissLaserWaterjetStampingEDMGrindingFinishingAssembly | ISO 13485 |
| Liberty CNC LLC Milling, Turning, Finishing · ISO 9001 | Cocolalla, ID | MillingTurningFinishing | ISO 9001 |
| Liberty Hill Company Milling, Turning, Swiss, Laser, Waterjet, Bending, EDM · ISO 9001, AS9100, ITAR | Huntington, WV | MillingTurningSwissLaserWaterjetBendingEDM | ISO 9001, AS9100, ITAR |
| Lindsay Machine Works, Inc Milling, Turning, Laser, Waterjet, Bending, Welding, Grinding | Independence, MO | MillingTurningLaserWaterjetBendingWeldingGrinding | - |
| Linear Machining Technology LLC Milling, Turning, EDM, Grinding, Finishing · ISO 9001 | Irwin, PA | MillingTurningEDMGrindingFinishing | ISO 9001 |
| Lively Machine Milling, Turning, Bending, Finishing | Evansville, IN | MillingTurningBendingFinishing | - |
| LNP Machining Milling, Turning, Welding, Finishing · ISO 9001, AS9100, ITAR, ISO 13485 | San Jose, CA | MillingTurningWeldingFinishing | ISO 9001, AS9100, ITAR, ISO 13485 |
| Loftis Steel & Aluminum, Inc. Milling, Laser, Waterjet | Nashville, TN | MillingLaserWaterjet | - |
| Loughmiller Machine, Tool & Design Milling, Turning, Waterjet, Welding, EDM, Finishing | Loogootee, IN | MillingTurningWaterjetWeldingEDMFinishing | - |
| Loutech LLC Milling, Turning, Swiss, Finishing · ISO 9001, AS9100, ITAR | Chino, CA | MillingTurningSwissFinishing | ISO 9001, AS9100, ITAR |
| Lowery's Job Shop Milling, Turning, Laser, Welding, Grinding, Finishing | Saint Louisville, OH | MillingTurningLaserWeldingGrindingFinishing | - |
| LP Precision, Inc Milling, Turning, Grinding, Finishing | Santa Clara, CA | MillingTurningGrindingFinishing | - |
| Ltmt Machining LLC Milling, Finishing | Santa Clara, CA | MillingFinishing | - |
| Luna's Sheet Metal Inc Milling, Turning, Bending, Laser, Welding | Santa Clara, CA | MillingTurningBendingLaserWelding | - |
| LX3 Tooling Milling, Turning, Laser, Welding, Grinding · CMMC | Aledo, TX | MillingTurningLaserWeldingGrinding | CMMC |
| M & M Sheet Metal, Inc Milling, Laser, Bending, Welding, Forging · ISO 9001, ITAR, CMMC | Williamsport, PA | MillingLaserBendingWeldingForging | ISO 9001, ITAR, CMMC |
| M & R Engineering Milling, Turning, Swiss, Finishing, Assembly · ISO 9001, AS9100, ITAR, NADCAP | Orange, CA | MillingTurningSwissFinishingAssembly | ISO 9001, AS9100, ITAR, NADCAP |
| M&M Full Service Machine Shop Milling, Bending, Welding, Grinding, Finishing | Satellite Beach, FL | MillingBendingWeldingGrindingFinishing | - |
| M&M Machining, Inc Milling, Turning, Welding, Finishing | Ventura, CA | MillingTurningWeldingFinishing | - |
| Machine & Tool Manufacturing Company Milling, Laser, Waterjet, Welding, Finishing | Adel, GA | MillingLaserWaterjetWeldingFinishing | - |
| Machine Repair & Design Milling, Turning, Waterjet, Welding, Finishing, Assembly · AS9100 | Sumner, WA | MillingTurningWaterjetWeldingFinishingAssembly | AS9100 |
| Machine Specialties, LLC Milling, Turning, Swiss, Welding, EDM, Grinding, Finishing, Assembly · ISO 9001, AS9100, NADCAP | Whitsett, NC | MillingTurningSwissWeldingEDMGrindingFinishingAssembly | ISO 9001, AS9100, NADCAP |