Rapid prototyping: a part in your hands in one to three days
Before spending on machining or tooling, print the geometry and check the fit. SLA, SLS, FDM and metal printing cover form, fit and function at different levels of fidelity.
Which printing route for which question
| Route | Material | Best for | Limits |
|---|---|---|---|
| SLA | Photopolymer resin | Smooth surfaces, fine detail, visual models | Brittle, UV-sensitive over time |
| SLS | Nylon PA12 | Functional parts, snap fits, living hinges | Grainy surface, porous |
| FDM | PLA, ABS, PETG, PC | Fast and cheap form checks, jigs | Layer lines, weaker in Z |
| Metal (SLM/DMLS) | Aluminium, stainless, titanium | Functional metal prototypes | Cost, post-processing, residual stress |
| CNC prototype | Any machined grade | Real material, real tolerance | 3–7 days, higher cost at 1 pc |
When to print and when to machine
If the question is whether the cover closes or the connector reaches, a printed part answers it in a day. Printing the whole assembly before any machining spend is the cheapest mistake-avoidance available.
Printed nylon is anisotropic: strong in-plane, weak across layers. A bracket that holds a load should be machined in the final alloy, or the test is measuring the printing, not the design.
Printed parts hold roughly ±0.1 mm at best and rarely a controlled surface finish. If the prototype is also the first article, machine it in the production material and process.
Print for the design review, machine for the engineering validation, and tool only after the design stops moving. Each step is cheaper than the one after it, so take them in order.
Cost and time at different stages
| Stage | Method | Lead time | What you learn |
|---|---|---|---|
| Concept model | FDM or SLA | 1–2 days | Proportions, packaging, visual fit |
| Engineering prototype | SLS or CNC | 2–7 days | Fit, function, assembly sequence |
| Validation units | CNC in final material | 3–7 days | Tolerance, finish, real material behaviour |
| Pre-production | CNC small batch | 7–15 days | Process capability, inspection method |
| Production | Casting, moulding or CNC volume | 15–30 days | Unit cost, repeatability |
Questions we get on this process
For metals, yes via SLM/DMLS, but the properties differ from wrought material because of porosity and residual stress. For anything that must behave like the production part, machine it instead.
Around ±0.1 mm on SLS and SLA in the build plane, worse across layers and on large parts. That is fine for fit checks and not fine for a bearing bore.
Yes. Send a sketch, photographs or a sample and the engineering team builds the CAD model, confirms it with you, then prints or machines from it. That work is charged and partly credited against production.
Yes: sanding, primer, paint and dyeing are all possible. Anodizing is not, because there is no aluminium oxide layer to grow on a polymer part.
Send the file, get a printed part in 1–3 days.
Tell us what the prototype has to prove — fit, function or appearance — and the route will be chosen for that, not for the cheapest print.
From the shop notes
Longer answers to the questions these pages raise.