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Safety: parts not to have remade
Most broken clips, knobs and brackets are fine to remake. Some parts are not, whatever the material or the maker's skill. Buy certified originals for these.
Last reviewed 12 October 2026.
Never remade by a maker
Vehicle safety parts
Brakes, steering, suspension, seat belts, wheels and hubs, airbag parts. Use the manufacturer's part or a type-approved equivalent, fitted by a qualified mechanic.
Gas appliances and fittings
Gas fittings, valves and burner parts. In Great Britain, work on gas installations and appliances must be done by a Gas Safe registered engineer under the Gas Safety (Installation and Use) Regulations 1998; other countries have similar licensing.
Mains electrics
Plugs, sockets, live-side housings, insulation, cable strain reliefs on live parts, heater and element mounts. Shock and fire risk.
Pressure and high heat
Pressure cookers, boilers, pressure-relief valves, compressed-air and hydraulic fittings, anything inside an oven or next to a heating element.
Children's safety
Toys for young children and childcare products: cots, car seats, high chairs, stair gates and buggies. Small parts are a choking hazard and the rules on strength and materials are strict. In the EU, toys for children under 14 come under the new Toy Safety Regulation, (EU) 2025/2509, from 1 August 2030.
Medical and mobility devices
Wheelchairs, walkers, hoists, care beds, hearing aids and CPAP parts are regulated medical devices; in the US, for example, a mechanical wheelchair is a Class I medical device. Only non-structural extras such as a bag hook or cup-holder clip are reasonable maker jobs.
Structural and overhead loads
Ladders, climbing and lifting gear, bike stems, handlebars, seatposts and forks, shelving that holds heavy loads overhead, child gates.
E-bike and e-scooter batteries
Battery cases, mounts and chargers. Fire and fall risks. Use the manufacturer or an authorised dealer.
Why printed parts need care
A UK government research paper on 3D-printed spare parts for consumer appliances (BEIS/OPSS Research Paper 2020/039, September 2020) found that none of the jurisdictions it reviewed (the UK, the EU, the US, Canada, Japan and China) has law specific to 3D printing: general product safety and liability law applies. It lists risks including porosity, weak bonding between layers, and the effects of moisture, UV light and ageing, which can lead to electric shock, burns or the appliance malfunctioning.
The same paper notes that copying a traditional part's shape without redesigning it is generally considered inappropriate. A good maker looks at the material, wall thickness and print direction, not just the geometry, and will ask how the part is loaded.
Heat: the limit people forget
Common printed plastics soften at temperatures a car interior, a motor housing or a sunny window can reach. Prusa Research's material guides give this practical guidance (not test ratings):
| Material | What the manufacturer's guide says | Good for |
|---|---|---|
| PLA | “Gets soft and deforms at temperatures over 60 °C”; degrades under UV; not for technical or outdoor use | Fit-check prototypes and indoor cosmetic parts only |
| PETG | Suitable for indoor and most outdoor use “with temperatures below 80 °C”; resists water and humidity | Clips, brackets and covers, including garden parts |
| ASA | UV and temperature resistance “up to 93 °C”; suitable for outdoor use | Exterior car trim, garden, marine and caravan exterior parts |
| Nylon | Resilient and resistant to abrasion, low friction; absorbs water if stored badly | Gears, bushings, hinges and wear parts |
| Polycarbonate | High toughness, tensile strength and heat resistance; needs experience to print | Tough housings and parts near moderate heat |
Printing temperatures are not service temperatures. For parts near engines, exhausts, ovens or heating elements, ask a machinist about metal, or buy the original.
Food contact
Be careful with anything that touches food or drink. Printed layer lines can trap residue, and not every filament or colourant is made for food contact. Ask the maker which material they can document for food use, or buy the original part. For anything used with food every day, the original is usually the better choice.
What makers on The Spool List can and can't take
- Makers can decline any job, and should decline the categories above.
- Firearm and weapon parts are not allowed on The Spool List.
- The Spool List's own guidance for spare parts: parts for brakes, gas, structural loads or medical implants should come from certified suppliers.
- If you are not sure whether a part is safety-critical, ask a qualified repairer first, or run the can this part be remade? checker.
Broken part in your hand?
Photograph it, measure it, post it once.
Post the part free on The Spool List. Makers quote with a price and a lead time, and the platform holds your payment until you confirm delivery.
Sources
- UK BEIS/OPSS Research Paper 2020/039: 3D printing of spare parts for consumer appliances (September 2020)
- Lancaster City Council: gas safety, Gas Safety (Installation and Use) Regulations 1998 (accessed 12 October 2026)
- Intertek: EU publishes the Regulation on the safety of toys, (EU) 2025/2509 (16 December 2025)
- US eCFR 21 CFR 890.3850, mechanical wheelchair (Class I medical device)
- Prusa Research knowledge base: PLA (accessed 12 October 2026)
- Prusa Research knowledge base: PETG (accessed 12 October 2026)
- Prusa Research knowledge base: ASA (accessed 12 October 2026)
- Prusa Research knowledge base: polyamide (nylon) (accessed 12 October 2026)
- Prusa Research knowledge base: polycarbonate (accessed 12 October 2026)
- The Spool List: replacement and spare parts made to order
Figures are quoted as the sources state them, checked 12 October 2026. Spotted something out of date? The rules and schemes change often; check the source.