Guide
Custom manufacturing from China: what you need before you start
You do not need a finished CAD model to start. You need four decisions and one clear statement of what the product must do. Everything else can be worked out with the factory — and it is cheaper to work it out before tooling is cut.
The minimum viable brief
- Function. What the part or product must do, in one sentence. "Hold a 12 mm cable against a wall without cracking below −10 °C" is a good brief.
- Critical dimensions. Only the ones that matter. Two or three tolerances that must hold, not a full drawing.
- Material expectation. ABS, PP, silicone, 304 stainless, aluminium 6061, cotton twill. If you do not know, describe the environment and let the factory propose.
- Quantity and cadence. First run, expected annual volume, whether you will reorder. Cadence changes tool design.
- Market and compliance. Where it will be sold determines which certifications are needed, and that decision is expensive to reverse.
Which process fits which quantity
| Process | Sensible from | Tooling cost, indicative |
|---|---|---|
| 3D printing / SLA | 1 unit | None — file only |
| CNC machining | 1–500 units | None, but high unit cost |
| Vacuum casting / urethane | 10–200 units | Low — silicone mould |
| Injection moulding | 1,000+ units | USD 1,500–20,000+ depending on part size and complexity |
| Die casting / stamping | 2,000+ units | USD 2,000–15,000 |
| Sewing / cut-and-sew | 100+ units | Pattern and grading, low |
| PCB assembly | 5+ boards | Stencil and programming only |
The five things that decide whether a custom project succeeds
- A physical sample before mass production. Non-negotiable for anything with a tolerance or a finish.
- Tool ownership in writing. State that the tool is your property and is returned or transferred on request.
- Written change control. Any design change after tooling is cut costs money; agree in advance who pays for what.
- An inspection standard. "Looks good" is not a specification. Define what a defect is, and the AQL you will accept.
- A realistic first order size. Tooling plus a first run that is slightly too large to be comfortable, rather than a reorder three weeks later at a worse unit price.