Prototype validated and you need a few hundred? Get production-grade CNC machined and sheet metal parts in batches, with the inspection reports and certificates your buyer asks for — quoted in minutes.
The only decision that changes the price by more than a few percent. Machining has no tool to pay off and lets the design keep moving; tooling wins on per-part price once the run is long enough to absorb it. For a rigid plastic part the lines cross at about 250 units. Metal parts stay machined or fabricated far longer.
| Run size | Recommended route | Typical lead time | Why |
|---|---|---|---|
| 20–50 units | CNC machining / sheet metal | ~7–10 business days | Setup is already amortized by unit 10; the design can still change between batches at no cost beyond the parts.Also consider: Urethane casting for soft or clear parts. |
| 50–250 units | CNC machining / sheet metal | ~2–3 weeks | Still cheaper than any tooled route for a rigid part — the $2,500 aluminum tool has not paid for itself yet.Also consider: Start quoting rapid tooling in parallel. |
| 250–500 units | Rapid aluminum tooling (plastics) | ~3–4 weeks incl. tool | Past the ≈250-unit crossover a molded part costs less all-in — but only if you are done changing it. Metal parts stay machined.Also consider: CNC if the design is not frozen or the part is metal. |
| 500+ units | Tooled production | 4–8 weeks | This is where per-part price, not flexibility, wins. See the injection molding cost guide for the steel-tool crossover.Also consider: CNC for metal; rapid → steel tooling at ≈4,000 units. |
Total program cost, 0–600 units — machining vs rapid tooling
Below ≈250 units CNC machining is cheaper because there is no tool to pay off; above it the $2,500 aluminum tool starts earning its keep. Urethane casting rises steepest — it competes on materials (soft, clear) and geometry, not on price for a rigid part. Cost functions: CNC $60 + $13.50/part · casting $400 + $47.50/part · rapid aluminum tool $2,500 + $3.50/part (palm-size rigid plastic housing, same assumptions as the injection molding cost guide).
Full tooling economics — rapid aluminum versus production steel, and the second crossover near 4,000 units — are in the injection molding cost guide. Cast metal parts follow the same logic at higher volumes; see the metal casting cost guide.
Three reference parts at low-volume quantities, unit price indexed to the smallest batch (= 100). The shape of every curve is the same: a big drop into 100 units, then a long flat tail — which is why splitting 500 into batches costs so little.
−26%
The bracket unit price drops 26% from 25 to 100 units. Most of the remaining setup and fixturing cost is gone by unit 100.
−13%
Only 13% more per part. Ordering 500 at once instead of 5 × 100 saves little — and freezes a design you may still want to change.
≈ 3×
A batch of 100 brackets costs about 2.9× a batch of 25; the machined enclosure about 3×. No tooling line on the invoice.
Aluminum 6061-T6 · 50 × 40 × 10 mm · 3-axis milled · 6 holes, 1 pocket · as-machined · ±0.1 mm general
Cost drivers: CNC machining cost guide
Aluminum 6061-T6 · 120 × 80 × 40 mm · deep pocketing, M3 tapped holes · bead blast · ±0.05 mm on bores
Cost drivers: CNC machining cost guide
Mild steel · 2 mm · laser cut, 2 bends · 4 mounting holes
Cost drivers: Sheet metal cost guide
CNC indexes come from the FabDigit quote engine’s batch-decay ratios (September 2026) for the exact reference geometry, rounded. Sheet metal indexes re-base the sheet metal cost guide’s curve. They show how the price moves, not what your part costs — your part is priced on its own geometry and confirmed by engineering review.
At 100 units the question stops being “does this part work” and becomes “can I prove every part matches.” These are the inspection levels and certificates in the FabDigit quote form — pick them with the quantity, and the reports arrive as signed PDFs with the parts.
| Inspection level | Cost | What you get | Use it when |
|---|---|---|---|
| Standard inspection | Included | In-process checks; final verification on critical features. No document ships. | Internal fixtures, brackets, non-critical parts. |
| Dimensional report | $ | Key dimensions from your drawing measured and delivered as a signed PDF. | Any part with a tolerance your assembly depends on. |
| CMM report | $$ | CMM-measured dimensional report — highest measurement confidence. | Bores, sealing faces, ±0.025 mm callouts, mating stacks. |
Certificates available on any order:
| Certificate | Scope |
|---|---|
| Certificate of Conformance | released with the delivery |
| Material certification | mill cert, EN 10204 3.1 |
| Material traceability | heat / lot chain of custody |
| Hardware certification | inserts, fasteners, standoffs |
| US-melted material (DFARS) | on request |
| US-made material (domestic) | on request |
How a batch order runs, upload to reorder:
A prototype forgives anything. A batch multiplies every decision by the quantity — material waste, inspection minutes, finish lot charges. Six changes that cut batch cost without changing what the part does.
Moving from a first prototype rather than a validated design? Start with prototype manufacturing — process choice and single-part pricing for v1.
Roughly 20 to 500 units of a validated design — past the prototype stage but below the volume where injection molding or die casting tooling pays for itself. For rigid plastic parts the crossover from CNC machining to rapid aluminum tooling is about 250 units; metal parts typically stay machined or fabricated well beyond 500.
No. FabDigit quotes from one part upward. Low-volume batches simply price lower per part because programming, fixturing, and first-piece inspection are spread across the run.
It depends on the part — upload CAD for the price of yours. What carries over is the curve: on a small aluminum bracket (50 × 40 × 10 mm, 6061-T6) the unit price at 100 is 26% lower than at 25 and only 13% more falls off by 500, so 100 parts cost about 2.9× a batch of 25. A palm-size machined enclosure follows the same shape.
For a rigid plastic part, around 250 units: below that the machined part is cheaper all-in because there is no tool to amortize; above it a rapid aluminum tool (roughly $1,500–5,000) wins on total cost. Switch only when the design is frozen — a design change after tooling costs a tool, a design change before tooling costs nothing.
Typically 2–3 weeks for 100–250 machined or sheet metal parts and 3–4 weeks for 500, plus 3–5 days for anodize, powder coat, or plating. Runs of 20–50 usually ship in 7–10 business days. The quote states the actual date for your part before you commit.
A batch runs on one machine and fixture set, and the project keeps the same drawings, spec, and inspection plan for reorders. Add a dimensional or CMM report to get measured evidence on the critical dimensions.
Certificate of Conformance, material certification (EN 10204 3.1 mill cert), material heat/lot traceability, hardware certification, dimensional or CMM inspection reports, and DFARS US-melted or domestic material on request. All are selected in the quote form and delivered as PDFs in your account.
Upload CAD, set the quantity, choose inspection and certificates — and get an engineering-reviewed quote before you commit.
