--- title: "Design 3D printed replacement parts from a description" description: "Broken knob, clip, hinge or foot? Describe it with a few measurements and SpeakCAD generates a printable STL replacement in minutes. From $7.99 a month." canonical: https://speakcad.com/use-cases/replacement-parts published: 2026-09-03 updated: 2026-09-23 publisher: SpeakCAD --- # Design 3D printed replacement parts from a description > Broken knob, clip, hinge or foot? Describe it with a few measurements and SpeakCAD generates a printable STL replacement in minutes. From $7.99 a month. The part that broke is rarely on Thingiverse in the exact size you need. With SpeakCAD you measure the original with calipers, type the numbers, and get a replacement that fits the first or second time. ## Why replacement parts are the best 3D printing use case Appliances, furniture and tools fail at their cheapest plastic component: a knob, a clip, a foot, a hinge pin. Manufacturers charge a fortune for spares or do not sell them at all. A 3D printer plus a few grams of PETG solves the problem for cents, but only if you can model the part. That modelling step is where most people give up. Learning Fusion 360 to draw a knob is a weekend, not an evening. SpeakCAD shortens it to minutes: start from a box or a cylinder and drill or cut it with the numbers you measured, or describe the geometry and the AI writes a parametric model that respects those numbers exactly. ## How to measure for a replacement - **Mating dimensions first.** The shaft, the hole, the slot the part has to fit. Measure these with calipers and give them to the millimetre (or tenth). - **Overall envelope second.** Width, height, depth. Approximate is fine; you can tweak later. - **Fit type.** Tell SpeakCAD whether the part must press on (tight), slide (loose) or snap. It applies the right clearance automatically: about 0.2 mm for press fits, 0.4 to 0.6 mm for sliding fits. - **Material and orientation.** Mention if the part takes load so the AI adds thickness or fillets where it matters. ## Re-download free after the test print Print the first version, test the fit, and come back to the chat: "the shaft hole is 0.3 mm too tight" or "make the lip 1 mm longer". Each of those is one request (2 credits), or nothing at all if you type the new number in the dimensions panel yourself. Small corrections re-download for free, so a replacement part typically costs a single download even with two or three fit iterations. ## Common replacement parts people generate - Appliance knobs and dials (oven, washer, mixer, amplifier) - Clips and hooks (fridge shelves, curtain rails, cable guides, blinds) - Feet and glides (furniture, laptops, kitchen appliances) - Hinge pins and bushings - Battery covers and remote-control lids - Vacuum cleaner adapters and attachments - Drawer runners and stops ## Prompts to try - A replacement knob 30 mm diameter, 18 mm tall, 6 mm D-shaft with a 0.5 mm flat, 12 mm deep, with a pointer line on top. ([open in SpeakCAD](https://app.speakcad.com/signup?next=%2F%3Fprompt%3DA%2520replacement%2520knob%252030%2520mm%2520diameter%252C%252018%2520mm%2520tall%252C%25206%2520mm%2520D-shaft%2520with%2520a%25200.5%2520mm%2520flat%252C%252012%2520mm%2520deep%252C%2520with%2520a%2520pointer%2520line%2520on%2520top.)) - A fridge shelf clip: 25 mm wide hook that grips a 3 mm glass shelf, with a 10 mm tab that slots into a 4 x 12 mm hole. ([open in SpeakCAD](https://app.speakcad.com/signup?next=%2F%3Fprompt%3DA%2520fridge%2520shelf%2520clip%253A%252025%2520mm%2520wide%2520hook%2520that%2520grips%2520a%25203%2520mm%2520glass%2520shelf%252C%2520with%2520a%252010%2520mm%2520tab%2520that%2520slots%2520into%2520a%25204%2520x%252012%2520mm%2520hole.)) - A washing machine foot, M10 threaded stud 30 mm long, 50 mm diameter base, 15 mm tall, rubber pad recess 2 mm deep. ([open in SpeakCAD](https://app.speakcad.com/signup?next=%2F%3Fprompt%3DA%2520washing%2520machine%2520foot%252C%2520M10%2520threaded%2520stud%252030%2520mm%2520long%252C%252050%2520mm%2520diameter%2520base%252C%252015%2520mm%2520tall%252C%2520rubber%2520pad%2520recess%25202%2520mm%2520deep.)) ## FAQ ### Can I upload a photo of the broken part? Yes. Attach a photo and give the key measurements in the message; the AI uses the photo for the shape and your numbers for the dimensions. ### What tolerance should I ask for? For a shaft or peg that must not spin, ask for a press fit (about 0.2 mm clearance). For sliding parts, 0.4 to 0.6 mm. If you do not specify, SpeakCAD picks the fit that matches your description. ### Does it handle threads? Yes for coarse printed threads (M8 and above) and for thread-insert or heat-set pockets. For small threads it is usually better to print a hole and tap it, which you can ask for. ## About SpeakCAD SpeakCAD is the most intuitive CAD for 3D printing, made for people who own a 3D printer and need a part that fits something they have: tap a face and type a size to shape it with simple tools, or describe it to the AI, on your phone or computer, and download a print-ready STL, 3MF or G-code sliced for your printer. SpeakCAD works inside ChatGPT and Claude as a plugin (an MCP server): ask the assistant for a part with its measurements and SpeakCAD's own CAD AI designs it, shows it in 3D in the chat and hands over a print-ready STL, 3MF or G-code sliced for your printer. - Live demo, no account: https://speakcad.com/demo - In ChatGPT, Claude and other MCP clients: https://speakcad.com/chatgpt-plugin, https://speakcad.com/claude-connector, https://speakcad.com/mcp-server - Pricing: https://speakcad.com/pricing - FAQ: https://speakcad.com/faq - Site index for AI assistants: https://speakcad.com/llms.txt