Guides / File prep
What file do you need for 3D printing?
5 min read · Reviewed June 2026
If someone's asked you to 'just send the STL' and you're not sure what that means, this is for you. A 3D printer needs a digital model of your object, and that model comes in a handful of common file formats. Here's which ones we accept, what separates a printable file from a broken one, and your options if you don't have a file yet.
The formats we accept
- STL — the most common 3D printing format by far. It describes the surface of your object as a mesh of triangles. If you only have one file, this is usually it.
- OBJ — like STL but can carry colour and texture data, handy for multi-colour or textured models.
- 3MF — a modern format that bundles the model plus print settings and colours in one tidy file. Great when it's available.
- STEP / STP — a precise, engineering-grade format from CAD software. Ideal for functional and mechanical parts where exact dimensions matter.
What makes a file actually printable
Not every 3D model is ready to print, even in the right format. A few things make the difference between a clean print and a failed one:
- Watertight (manifold) — the mesh should be fully closed, with no holes or gaps in the surface. Think of it as needing to hold water.
- Correct scale and units — models often arrive far too big or too small because the units were ambiguous. Tell us the intended real-world size in millimetres and we'll confirm scale before printing.
- Sensible wall thickness — very thin walls can be too fragile to print or to survive use. We'll flag anything that looks too delicate.
- One clear orientation — knowing which way is 'up' helps us print it with the best strength and surface finish.
Don't have a file? That's fine
Most people don't, and it's rarely a problem. Send us a clear photo from a couple of angles, or a sketch, along with the rough size you want. For simple shapes we'll model the part for you — often as part of the job — and show you what it'll look like before anything prints.
Got a physical object you want copied or replaced? A photo with a ruler or measurements next to it is usually enough to recreate it.
How to send it
Send your file or photos over WhatsApp, or upload them through our quote page. We'll check everything, fix small issues on our side where we can, and come back with a price and a turnaround — usually within the hour.
Frequently asked
What is an STL file?
An STL file is the most common 3D printing format. It represents your object's surface as a mesh of triangles. Most 3D models you'll be given or download come as STL.
Which 3D file format is best for printing?
STL is the universal default and works for almost everything. 3MF is excellent when you want settings and colour bundled in. STEP is best for precise, mechanical parts. Send whatever you have and we'll work with it.
Can you print from a picture instead of a file?
Yes. For simple objects we can model from a clear photo or sketch plus the dimensions you want. Send a couple of angles and a measurement and we'll take it from there.
My file might not be watertight — is that a problem?
Often not. We check and repair common mesh issues on our side before printing. If something can't be fixed cleanly, we'll tell you and suggest the simplest way forward.
// Keep reading
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