Which fits your batch?
| Factor | Vacuum Casting (silicone mold) | CNC Machining |
|---|---|---|
| Best batch size | 20–100 copies | 1–20, or very large parts |
| Tooling | Silicone mold, days, low cost | No mold, but programming + fixturing |
| Materials | ABS-like, PP-like, rubber-like urethanes | Aluminum, steel, brass, engineering plastics |
| Tolerance | ±0.2–0.5 mm typical | ±0.05 mm achievable |
| Consistency | Good across a run via one master | Excellent, repeatable |
| Lead time | 5–7 days after master | 2–4 days per setup |
Not sure printing or machining is better for a single part? See our 3D printing vs CNC guide.
Use this for your batch
Pick vacuum casting when…
You need many copies of a finished design, want production-like feel (ABS-like, PP-like, rubber-like), and budget per part matters more than ±0.05 mm. Tooling is a soft mold, not hardened steel.
Pick CNC when…
The part is large, metal, needs tight tolerance, or uses a material casting cannot replicate. For one prototype, 3D printing is often fastest.
Materials that mimic production
Cast urethanes cover most pilot needs: rigid, flexible, high-heat and clear grades. We can also paint, plate and texture the surface so copies look like molded production parts.
Scaling the run
One silicone mold gives ~15–25 good shots. For bigger quantities we cast several molds from the same master, so volume grows without re-engineering the design.
Where each process pulls ahead
Vacuum casting
Best cost-per-part for 20–100 copies with production-like materials and finishes. See our vacuum casting service.
CNC machining
The choice for metal, large parts and ±0.05 mm. Higher per-part cost at low volume but unmatched accuracy.
3D printing
Fastest and cheapest for the first prototype and very low volumes. Bridges into casting or CNC as the design matures.
Common questions
Choose vacuum casting when you need 20-100 near-identical copies of a validated design, want production-like materials (ABS-like, PP-like, rubber-like), and care about per-part cost more than ultra-tight tolerance. The silicone mold is cheap and fast to make.
Cast urethanes mimic production plastics: rigid ABS-like and PC-like, flexible PP-like and rubber-like, and filled grades for higher heat or clarity. Metal parts are not possible — that is where CNC wins.
A typical silicone mold yields 15-25 good copies before detail degrades. For larger runs, we cast multiple molds from the same master so volume scales without re-tooling the design.
Usually yes for 20-100 parts. The silicone mold costs a fraction of hardened steel tooling and is ready in days, so per-part cost drops sharply versus machining each copy. See our pricing reference for ranges.
CNC wins for large parts, metal parts, features needing ±0.05 mm, or materials casting cannot replicate. For a single prototype, 3D printing is often fastest and cheapest.