What can you 3D print in flexible TPU, and when should you cast instead?

TPU 3D printing makes parts that bend, squash and spring back: grips, seals, bumpers, cases and straps. TPU 95A is our standard flexible filament and is in the instant quote, while softer, harder and clear grades are on request. For many identical soft parts, or a true rubber feel, we cast them instead through our silicone moulding service.

TPU grades at a glance

Shore hardness: how hard a flexible material feels when you press into it. On the A scale, a lower number is softer. The D scale picks up where A runs out, for harder grades.

Upload your part and get a price in TPU 95A

What TPU is: a rubbery, springy filament

TPU (thermoplastic polyurethane) is a rubbery plastic that we print on our filament printers (fused deposition modeling, FDM), layer by layer like PLA or PETG. Where a rigid print would crack, a TPU part bends and returns to shape. Its maker’s data sheet says TPU 95A stretches over 650% before it breaks along its layers, and over 480% across them.

The child’s ankle brace below was printed in TPU so it flexes with the foot. Our filament comparison sets TPU beside the rigid filaments.

What TPU suits: grips, seals and bumpers

Pick TPU when the part has to give a little:

• Grips and handles: soft-touch sleeves and grips that don’t slip.
• Seals and gaskets: for dust and splashes, where a flat face presses against a lid.
• Bumpers, feet and pads: to soak up knocks and stop scratches.
• Phone and device cases, and protective covers: they stretch on and cushion a drop.
• Cable strain reliefs: the soft sleeve where a cable leaves a plug or housing.
• Wearable bands and straps: they bend around a wrist or a tool.
• Fold-over flaps: a thin, flexible strip that lets one piece fold over another.

Where TPU falls short: fine detail and heat

TPU has honest limits, so check these before you order:

• Very fine detail: TPU prints slowly and softly, so tiny text and sharp small features blur. For fine detail in a flexible part, a flexible resin suits better: see our guide to resin types.
• Parts that must stay perfectly stiff: a bracket or frame that has to hold its shape belongs in PETG, ABS or an engineering filament.
• High heat: its maker publishes no softening figure for TPU 95A, so ask us before a TPU part goes anywhere hot.
• Paint: paint cracks off as the part flexes, so choose the filament colour instead.

Clear TPU: flexible and see-through

Clear TPU bends like the standard grade but lets light through. As printed, it comes out frosted rather than glass-clear, and the layers show as fine lines. It suits covers, connectors and soft parts where you want to see what sits inside.

The clear connectors at the top of this page were printed to stand in for a white machined plastic part. Clear TPU is on request, so check with us first.

Need clear, softer or harder TPU? Talk to us

Designing for TPU: walls set the softness

In TPU, how soft a part feels depends on how it is printed as much as on the grade:

• Wall thickness and infill change the feel. Thin walls and a light infill (the inner fill pattern) make a part softer and squashier. Thick walls or a solid print feel closer to the grade’s own hardness. Say in the notes how soft it should feel.
• Avoid long, thin overhangs. TPU sags when it prints over thin air, and supports are hard to peel off it. Design flat faces and gentle slopes, or a flat side to sit on the printer bed.
• Leave room for fits. TPU squashes, so a sleeve can grip a rigid pin more tightly than a rigid print could, but a fit that comes out loose is hard to fix later. The figures in our tolerances and clearances guide are for rigid filament, so tell us when a TPU part has to fit over or into something.
• Bend along the layers. TPU stretches further along its printed layers than across them, so tell us which way the part flexes and we turn it to suit.

Upload it and say in the notes how soft it should feel

Casting instead: for many soft parts

Printing suits one or a few soft parts. Casting suits more. We 3D print and finish an original, make a silicone mould around it, then cast copies (see how vacuum casting works). Choose casting when:

• You need many identical soft parts. One silicone mould gives about 20 to 50 casts, and every cast matches.
• You want a true rubber feel. Rubber-like polyurethane casts run from Shore A 40, soft and squashy, to Shore A 90, firm but still bendable.
• The part touches food or skin. Ask us about silicone casts: tell us what the part will touch and we check the grade.

The screen covers below were cast in black rubber-like polyurethane at Shore A 80, as a run of 10. Our vacuum casting materials guide compares every cast material.

Many soft parts? See silicone moulding

Still choosing between rubbery and rigid? Our materials guide compares every family we offer, and our 3D printing service shows what we print in our own studio.