Urethane casting — injection-molding looks, without the tooling.

Polyurethane resins cast in silicone molds taken from a master pattern — tens to hundreds of parts that look and behave like ABS, PP, rubber or clear plastic, with no steel tool to pay for.

Get my urethane casting quote →See resins & mold life ↓

Quick definition

Urethane (vacuum) casting makes a silicone mold from a master pattern — usually 3D-printed or machined — then casts polyurethane resin into it under vacuum. Each silicone mold yields tens of parts before it wears, so it's the bridge between 3D printing and injection molding: production-quality plastic parts in low volumes, without the cost or lead time of a hard tool.

Cast in siliconeNo hard tooling
RigidABS/PP-likeHousings
FlexibleRubber-likeShore A
ClearOpticalLenses
Master pattern to parts in days, not weeks.
No steel toola silicone mold from your master, not a machined mould
~20–50 partsper silicone mold before it needs replacing
ABS · PP · rubberresins that mimic production plastics, rigid to soft
Days, not weeksfrom master pattern to cast parts

Production looks, at prototype volume

Between a printed part and a molded one.

A 3D print proves the shape but rarely looks or feels like the finished plastic; an injection tool delivers that finish but costs weeks and thousands up front. Urethane casting sits between them — silicone molds off your master give production-like parts in ABS, PP, rubber or clear resin, in the tens to hundreds, in days. OperGo casts them, color-matches and finishes them, and tells you when volume finally justifies switching to injection.

Print it or tool it
  • A 3D print that doesn't match the production plastic's look or feel
  • A steel injection tool ordered for a run of only 50 parts
  • Weeks of tooling lead time to validate a design
  • Clear, rubber-like or color-matched parts printing can't give
The OperGo way
  • Silicone molds off your master — real cast urethane parts
  • Production-like finish and feel at prototype volume
  • Master pattern to parts in days, not tooling weeks
  • Rigid, flexible, clear and color-matched resins, cast to spec

What we run

One casting route, resins to match the production part.

Rigid ABS/PP-like

Stiff polyurethanes that stand in for ABS, PP and PC — housings, enclosures and structural parts for pilot runs and pre-series.

Rubber-like

Flexible resins across a range of Shore hardnesses for grips, seals, gaskets and soft-touch parts.

Clear & optical

Water-clear resins for lenses, covers and light guides, polished to an optical finish.

Color-match & overmold

Parts pigmented to your color, textured, and overmolded — soft-touch on rigid — to look like the production part.

The spec sheet

Resins, mold life and finish.

Resins & mold life · Urethane Castingno hard tool
Rigid resinsPolyurethanes that mimic ABS, PP and polycarbonate for structural and housing parts, some in high-temp and glass-filled grades.
Flexible resinsRubber-like urethanes across a range of Shore A hardnesses, for seals, grips and gaskets.
Clear resinsWater-clear resins for lenses, covers and light guides, polished to an optical finish or tinted to a target.
Mold lifeA silicone mold yields roughly 20–50 parts before it degrades; more molds are taken from the master for larger runs.
Master patternTaken from an SLA print or a CNC-machined master — the better the master's finish, the better every cast part.

Full range of materials and finishes on Materials & finishes →

Picking a process

Urethane casting owns the gap — until volume tips to injection.

Urethane casting vs. 3D printing →

Printing is faster for one or two parts and true one-offs. Urethane casting gives a better, more production-like finish and material across tens of matching parts.

Urethane casting vs. injection molding →

Injection wins once you need thousands and can justify a steel tool. Below that, silicone molds deliver production-like parts with no tooling cost or lead time.

The master behind it →

Every silicone mold starts from a master — a clean SLA print or a machined pattern. We make the master and the parts in-house.

Urethane casting, answered

When should I use urethane casting instead of injection molding?

When you need tens to a few hundred parts, fast, with a production-like finish — but not the thousands that justify a steel injection tool. Silicone molds cost a fraction of hard tooling and are ready in days, so urethane casting bridges the gap between a prototype and a molded product.

How many parts can one mold make?

A silicone mold typically yields around 20–50 parts before it wears, depending on the resin and geometry. For larger runs we take several molds from the same master, so the quantity scales while the master stays the reference.

Can the parts really look like ABS, rubber or clear plastic?

Yes. Polyurethane resins are formulated to mimic rigid plastics like ABS and PP, flexible rubber across a range of Shore hardnesses, and water-clear optical resin. Parts are color-matched, textured and finished so they read as the production part, not a prototype.

What do I need to supply to start?

A 3D CAD model. We produce the master pattern — usually an SLA print or a machined part — make the silicone mold from it, and cast the parts. The cleaner the master's surface, the better every cast copy.

What tolerances and cosmetic quality can I expect?

Tolerances are looser than injection molding but fine for fit, form and function checks and pre-series units; cosmetic quality is high — color-matched, textured or polished. For tight-tolerance production, that is the point to move to injection.

When is it time to switch to injection molding?

Once your volume runs into the thousands, a steel tool's low per-part price beats re-casting silicone molds. Your engineer will flag the crossover and can build the injection tool when you're ready.

3D Printing →

The faster route for one or two parts and the master pattern.

Injection Molding →

Where you move once volume justifies a steel tool.

See all capabilities →

3D printing, injection molding and everything else we run.

Materials × process

Materials we run in urethane casting.

Sourced, produced and finished under one quote. Tap a material to see the other processes it runs on — material and process are two axes you combine, not one nested inside the other.

ABSPolypropylene (PP)TPE / TPUAll materials & finishes →

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