How to prepare a 3D model for printing (even if you're not an engineer)

3D printing is now used across many industries – from prototyping to personal projects. But even the best printer can’t save a badly prepared file. In this guide, we’ll walk you through how to prepare a 3D model for printing, what to watch out for, and when to turn to a pro like László 3D.

Why downloading an STL file isn’t always enough

It’s tempting to grab a ready-made file from Thingiverse or Printables, but be careful – not every STL is print-ready:

No scale: the model could be 10× too large or too small
Geometry errors: holes, flipped normals, or non-manifold edges
Not adapted for the chosen material or technology (e.g., thin walls on FDM)

If in doubt, send us the model. At László 3D, we’ll check printability for free and suggest improvements if needed.

What a good 3D model should include

Whether you're creating the model yourself or outsourcing it, make sure it meets the following criteria:

Closed volume (manifold) – the model must be watertight
No internal floating bodies – remove any loose parts inside
Reasonable wall thickness – at least 0.8 mm for FDM printing
No duplicate or overlapping surfaces – slicers don’t like it

The best formats to send are STL or 3MF. If you're using STEP or IGES, allow for conversion time.

How to fix a problematic model

Even flawed models can be salvaged with the right tools:

Meshmixer or Microsoft 3D Builder – for basic repairs
Fusion 360 – ideal for complex edits or redesigns
Netfabb (online or desktop) – automatic fixing of holes and meshes

We validate every model before printing and can modify it for you. Even a photo or sketch is enough – we can build a printable 3D model from scratch.

When to hire a professional modeler

Consider working with a pro if you need:

a part that needs precise fit (e.g., mount or adapter)
something reverse-engineered from a real object
a shape that’s hard to measure manually
just an idea in your head but no technical drawing

In such cases, investing in 3D modeling pays off. At László 3D, we have 15 years of experience with Fusion 360 and design parts that not only print well but also work as intended.

Common mistakes in 3D models

Missing walls or holes – the print may fail or be unstable
Microscopic parts – slicers ignore them or print blobs
Massive solid shapes – wastes material and time
Overly loose tolerances – parts won't fit together
No consultation – talk to us first, we’re happy to help

Working with us: how it goes

Send your model or sketch – via email or through our calculator
We check printability for free
We suggest any needed fixes
We send a price quote and preview
We print only after your approval

Our workflow is designed to deliver great results even if you’re not a technical expert.

Summary

Preparing a 3D model is the first (and often most crucial) step in the printing process. If you’re unsure about your file, don’t hesitate to reach out. We’ll assess the situation and recommend the best way forward. Whether you’re a DIY enthusiast, startup, or designer – we’re here to help.

Get a quote or send us your model today. Let’s bring your idea to life with professional precision.