Urethane casting cost guide
Cast urethane has a small fixed cost (a master and a silicone mold) and a per-part cost that stays flat, because every part is poured, cured and finished by hand and the mold wears out after 20–25 shots. That shape — cheap tooling, no economy past a few hundred — is exactly what decides where it beats 3D printing and where injection molding takes over.
The three lines on a urethane casting quote
Master, mold, parts. The first two are one-time; the third scales with quantity — and with the number of molds a quantity needs.
1 ×
Master pattern
An SLA print (or a CNC part for large or tight parts) sanded, primed and finished to the surface the parts will have. Sized to the part; a hand-sized master is priced like a good SLA print plus finishing hours.
per 20–25 parts
Silicone mold
Platinum-cure RTV silicone poured around the master in a frame, cured, cut open. Priced on silicone volume (the part’s bounding box plus a 20–30 mm wall) and cutting labour. Wears out; a 100-part order needs 4–5.
per shot
Cast part
Mixed, degassed, poured under vacuum, cured 1–4 h (oven), demolded, gate cut, sanded, finished. Resin by weight plus a fixed 20–60 minutes of hands-on labour — the reason the per-part price barely falls.
+
Options
Paint (any gloss), texture, colour matching, clear polishing, inserts, over-molding, second material. Each is per-part labour, usually 20–100 % on top of the bare casting.
Typical market ranges
Hand-sized reference part (~100 × 60 × 40 mm, 2.5 mm walls, ABS-like rigid urethane, as-cast with light sanding). Western service-bureau list prices, 2025–26, for comparison only.
| Line | Hand-sized part | Large part (~ 300 mm) | What moves it |
|---|---|---|---|
| Master pattern (SLA + finish) | $150 – $500 | $500 – $2,000 | Size, surface finish spec, CNC instead of SLA, split masters |
| Silicone mold (each, 20–25 shots) | $200 – $600 | $800 – $3,000 | Silicone volume (bounding box), cores, multi-part molds, inserts |
| Cast part, rigid ABS-like | $40 – $120 each | $150 – $500 each | Resin weight, cure time, gate/finish labour, hardness system |
| Cast part, elastomer (Shore A) | $45 – $140 each | $180 – $600 each | Soft systems are slower to demold and trim |
| Cast part, clear / optical | $80 – $250 each | $300 – $900 each | Polished master, UV-stable resin, post-polish and coat |
| Paint, per part | + $15 – $60 | + $50 – $200 | Colour match, gloss level, masking |
| Over-mold (soft on rigid), per part | + $30 – $100 | + $100 – $350 | Second mold and second pour |
| Threaded inserts, each | + $2 – $5 | + $2 – $5 | Placed in the mold before every pour |
Ranges compare processes and sizes; they are not FabDigit quotes — engineer-quoted per part. The quote flow returns the actual master, mold and per-part lines.
How the price moves with quantity
The fixed cost is small, so the per-part average falls quickly from 10 to about 50 parts. After that it is flat — every 25 parts needs another mold, and every part still takes the same hands-on time.
| Quantity | Molds needed | Relative cost per part | Read |
|---|---|---|---|
| 5 | 1 | 2.2 | Master and mold amortised over five parts — 3D print instead |
| 10 | 1 | 1.5 | The usual entry point; roughly where SLA/MJF prints stop being cheaper for a molded look |
| 25 | 1 | 1.0 | One mold used to its life — the sweet spot |
| 50 | 2–3 | 0.85 | Second mold; master reused |
| 100 | 4–5 | 0.78 | Flat from here — molds and labour scale with parts |
| 250 | 10–12 | 0.75 | Compare against an aluminum injection tool; usually close |
| 500 | 20–25 | 0.74 | Molding is almost always cheaper by now |
Illustrative curve. Two things flatten it: the mold count grows with quantity, and the pour-cure-finish labour is per part. Urethane casting never gets the per-part economy of a steel or aluminum tool.
Where urethane casting wins — and where it loses
Three processes compete in the 10–500 band. The decision is fixed cost versus per-part cost, plus the look and the material you need.
| Process | Fixed cost | Per part, qty 50 | Usually cheapest | Choose it when |
|---|---|---|---|---|
| 3D printing (MJF / SLS / SLA) | none | $5 – $20 | 1 – 10 parts | Iterating, functional prototypes, lattices — a print is fine and looks do not matter |
| Urethane casting | master + molds | $40 – $140 | 10 – 300 parts, molded look | Painted housings, clear lenses, soft grips, over-molds, colour-matched parts, before a tool exists |
| Injection molding, aluminum tool | tool | $3 – $15 | 300 – 500+ parts; earlier for simple parts | Design frozen, production plastic needed, thin walls, hundreds to tens of thousands |
| CNC machining, plastic | none | $25 – $90 | 1 – 30 simple prismatic parts | True engineering plastic (real ABS, PC, POM), tight tolerance, no cosmetic paint |
The crossover with injection molding is the real decision: at 100 parts urethane is usually cheaper all-in; at 500 the aluminum tool usually wins; between them, quote both. A part designed to the molding rules moves to the tool with no redesign.
What moves a urethane casting quote
Most of the price is labour minutes per part and silicone volume per mold. Both are geometry you control.
| Driver | Effect | What to do |
|---|---|---|
| Part size (bounding box) | mold cost ~ volume; large parts need thicker molds and split frames | Split very large parts and bond; nest small parts several per mold |
| Resin volume | material is 10–25 % of the part price | Uniform 2–3 mm walls; core out solid sections (also helps cure) |
| Undercuts and cores | +15–40 % mold cost for multi-piece molds and loose cores | Silicone strips shallow undercuts free; only deep internal features need cores |
| Surface finish | master finishing hours; paint per part | Texture hides sanding; paint only A-surfaces; “as-cast, sanded” is the floor |
| Colour | mixed-in pigment is nearly free; Pantone match + paint is per part | Cast in black or natural and paint only when the colour must be exact |
| Material system | ABS-like 1 × · PP-like 1.1 × · elastomer 1.2 × · clear 1.8–2.5 × · FR / high-temp 1.3–1.6 × | Specify behaviour (hardness, temperature, UL) and let the caster pick the system |
| Inserts / over-molding | per-part labour; over-mold doubles the molds | Heat-set inserts after casting are cheaper than cast-in unless position is critical |
| Tolerance | ± 0.3 mm is standard; tighter means a CNC master and drilling / reaming after | Put the tight fits on drilled holes and machined pads, not on cast faces |
| Quantity per order | flat past ~ 50; master re-used across orders | Order in multiples of a mold life (20–25); keep the master for repeat runs |
Seven ways to cut a urethane casting quote
In order of effect.
- Order in mold multiples. 25, 50, 100 — not 30 or 60. A mold used for six shots costs the same as one used for twenty-five.
- Design to the molding rules now. Uniform walls, radii, no deep undercuts. The mold is cheaper, the parts cure flat, and the design moves to injection molding without a redesign.
- Paint only what is seen. Mark A-surfaces; leave the inside as-cast in a matching pigment.
- Use the base resin tier. ABS-like rigid unless heat, flame or clarity demands otherwise; clear and high-temp systems are 1.5–2.5 ×.
- Keep the master. It survives many molds; a repeat order skips the master line entirely.
- Heat-set inserts after casting. Cheaper than placing brass in the mold every shot, unless the insert position is critical.
- Quote molding in parallel above ~ 150 parts. An aluminum prototype tool is often within reach; let the two quotes decide.
The design rules — master, walls, undercuts, inserts, tolerances — are in the urethane casting design guide; the tool-side of the crossover is in the injection molding cost guide.
Urethane casting cost — FAQ
How much does urethane casting cost?
For a hand-sized rigid part, typical service-bureau ranges are $150–500 for the master pattern, $200–600 per silicone mold (good for 20–25 parts) and $40–120 per cast part; elastomers, clear parts, paint and over-molding add per-part labour. These are market ranges for comparison — urethane casting is engineer-quoted, so upload the file for the actual figure.
Is urethane casting cheaper than injection molding?
Up to roughly 100–300 parts, yes — the master and silicone molds cost a fraction of an aluminum tool. Above about 300–500 parts the tool amortises and injection molding wins on per-part price ($3–15 vs $40–140). Between 100 and 500, quote both.
Is urethane casting cheaper than 3D printing?
Not per part — a print of the same geometry is usually cheaper. Urethane casting is chosen from about ten parts upward when the parts must look and feel molded: painted, textured, clear, soft, colour-matched or over-molded, in ABS-, PP- or PC-like materials or rubber. For a functional prototype where looks do not matter, print it.
Why does the per-part price stop falling?
Every silicone mold lasts 20–25 shots, so molds scale with quantity, and each part is poured, cured, demolded and finished by hand — 20–60 minutes of labour that no quantity amortises. The curve is steep to about 50 parts and flat after.
What drives the cost of a urethane casting?
Part size (silicone volume per mold), resin volume, undercuts and cores (multi-piece molds), surface finish and paint, colour matching, material system (clear and high-temp cost 1.5–2.5 × rigid ABS-like), inserts and over-molds, and tolerance (a CNC master and post-machining for anything tighter than ± 0.3 mm).
How many parts can one silicone mold make?
About 20–25 rigid urethane parts; fewer with abrasive glass-filled systems, more with soft elastomers. Order in multiples of the mold life — a mold used for six shots costs the same as one used for twenty-five.
What should I send for a urethane casting quote?
The STEP model, the quantity, the plastic behaviour you need (or the grade you would mold in), marked cosmetic faces and finish, inserts or over-mold details, and a drawing with the critical dimensions. A FabDigit engineer returns the master, mold and per-part lines, and the injection molding comparison if the quantity is near the crossover.
Ranges show the shape. The quote gives the number.
Upload the model with quantity and finish — a FabDigit engineer returns the master, mold and per-part quote, with the injection molding comparison when you are near the crossover.