One part, 50 or 5,000: 3D printing, silicone moulding or injection moulding?

Pick 3D printing for one part up to a handful, and silicone moulding to cast about 20 to a few hundred copies from one printed original. Past about 1,000 identical parts, injection moulding with a steel or aluminium tool costs the least per part.

3D printing, silicone moulding or injection moulding at a glance

The more a route costs before the first part, the less each part costs after it. Printing needs nothing up front, silicone moulding needs a printed original and a mould, and injection moulding needs a metal tool, the biggest cost of the three. Times are a rough guide for a normal-size part (about 10 to 15 cm across); nylon prints take 8 to 12 working days, and bigger parts take longer.

From a handful to about 20 parts, or from a few hundred to about 1,000, the best route depends on the part’s size and shape, so ask us.

Tell us the part and the quantity, and we suggest the route

3D printing: best for one part up to a handful

Printing needs no mould and no tool, so the first part costs the same as the tenth. That makes it the route for a prototype, a one-off or a few test parts. We print in filament (fused deposition modeling, FDM), resin (stereolithography, SLA) and nylon powder (selective laser sintering, SLS).

• Pick it for: prototypes, display models, a handful of working parts, and checking the fit before you commit to a mould.
• Changing the design costs nothing: edit the file and print again.
• Time: 4 to 7 working days for a normal-size part (about 10 to 15 cm across) in filament or resin; nylon powder takes 8 to 12. Bigger parts take longer, so check with us.

Its honest limits:

• Cost per part stays flat. The fiftieth part costs about the same as the first, so a long run gets expensive (what sets the price of a print in Singapore).
• Parts vary a little. Each print is made on its own, so the surface can differ slightly from part to part, where a mould repeats it exactly.

One part or a handful? Upload your file for an instant price

Silicone moulding: best for about 20 to a few hundred

Silicone moulding (also called vacuum casting or urethane casting) copies one printed original. We print and finish the original, pour liquid silicone around it to make a soft, flexible mould, then fill that mould with polyurethane or silicone again and again. There is no minimum order, and the price per part falls as the run grows.

• Pick it for: pilot runs, short production runs, rubber parts such as seals and grommets, and parts that must all look the same.
• Mould life: a silicone mould usually gives 20 to 50 good casts before fine detail softens (Formlabs’ casting guide puts it at roughly 50). For a few hundred parts we pour more moulds from the same original.
• Time: as a general guide, about 1 week to design the master, 2 to 3 working days for the mould, then 7 to 10 working days of casting. Smaller parts can be faster, so check with us.
• Several at once: small parts can share one mould, like the six leaves below.

Its honest limits:

• Sharp inside corners and straight walls with no taper can tear the silicone as the part comes out. We suggest small changes to the design.
• Cast plastics are look-alikes. A rigid cast is an ABS-like polyurethane, close to ABS but not the same plastic, so ask us if the part must meet a production data sheet.
• A faint parting line shows where the mould opens. We trim and sand it on every part.

See how silicone moulding works, step by step

Injection moulding: worth it past about 1,000

Injection moulding forces molten plastic into a metal tool. The tool is the big cost: once it is paid for, each part costs very little, which is why it wins past about 1,000 identical parts. We review the design for moulding, print samples to test it, and arrange the steel or aluminium tool, the sample parts for your approval and the production run.

• Pick it for: thousands of parts of a design that is final, in a real production plastic such as ABS, PP, PE or PC.
• Aluminium or steel: an aluminium tool is quicker to make and suits thousands to tens of thousands of parts; a steel tool lasts hundreds of thousands to millions, according to Protolabs’ tooling guide.

Its honest limits:

• The tool comes first. It has to be made and its first parts approved before the run starts, and a steel tool can take months (Protolabs).
• Changes are costly. A metal tool is hard to alter, so test the design in printed or cast parts first.
• The design must suit the tool: even walls, a slight taper on the sides so the part slides out, and no trapped undercuts. We check this before any metal is cut.

See how we take a part to injection moulding

Cast materials: hard, rubbery or clear parts from one mould

A silicone mould can be filled with four kinds of material, so one printed original can become a hard part, a rubbery one or a clear one.

Shore A is the hardness scale used for rubber: the lower the number, the softer the part. The grommet below is cast in soft polyurethane, so it flexes and grips without tearing.

Not sure which cast material? Tell us what the part has to do

The printed original: it sets the finish of every cast

A silicone mould copies everything on the original: its shape, its detail and every scratch or layer line. So the original is printed, then sanded and finished until it is exactly what every cast should look like. A smooth original gives smooth casts; a polished one gives clear casts.

• Why it matters: fixing a flaw once on the original fixes it on every part. A flaw left on the original is copied into every part.
• Filament or resin: a resin print (SLA) starts smoother, so it suits fine detail; a filament original is sanded smooth first (how we finish prints).
• No 3D file? We can design or reverse-engineer the part from a sample first, through product development.

Upload your original for an instant print price

How to decide: start from how many you need

• One part, or a few to test: 3D print it. Nothing to pay for before the first part, and the design can change freely.
• About 20 to a few hundred identical parts: silicone moulding from one printed original.
• A rubber part in any batch: silicone moulding in soft polyurethane or silicone. For one or two, a flexible print in TPU (a rubbery filament) may do.
• Thousands of parts of a final design: injection moulding.
• Not sure how many will sell: cast a few hundred first, then move to a tool once demand is proven. Protolabs gives the same advice on tools: aluminium to prove the design, steel once demand is established.
• A design still changing: stay with printing or silicone moulding until it settles, because a metal tool is costly to change.

Many products take all three steps in turn: a printed prototype to test, a cast pilot run to sell or trial, then injection moulding once the numbers are there. Our product development work covers the whole path, and FDM, SLA or SLS helps you pick the printing process first.

Tell us your quantity and we suggest the cheapest route