3DPrintShop Lab · Free tools

Free 3D printing tools. No sign-up, no upload.

Convert a model between STL, OBJ and 3MF, split a multi-part 3MF across build plates, or work out what a print costs. Small, sharp utilities for the jobs that come up between downloading a model and actually printing it — all running in your browser, with your files staying on your own device.

Free

3D File Converter

Convert STL, OBJ and 3MF in your browser — STL to 3MF, OBJ to STL, binary to ASCII, plus GLB and PLY. Nothing is uploaded.

Free

Split Model for Printing

Model too big for your printer? Cut it into pieces that fit, with connector pins added so they glue back together.

Free

3D Print Cost Calculator

Work out filament, electricity and machine cost per print, and what to charge for it.

on freeinvoice.cc

Which tool do I need?

“My slicer won't open this file.”: Use the 3D file converter. It reads STL (binary or ASCII), OBJ and 3MF, and writes any of those plus GLB and PLY. It also fixes the common case of a file with the wrong extension, because it identifies the format from the contents rather than the name.
“This model is 450 mm and my printer is 256 mm.”: Use the model cutter. It cuts the model into pieces that fit your bed and adds connector pins and matching sockets at each cut, so the printed pieces line up and glue back into the original.
“What does this print actually cost me?”: Use the 3D print cost calculator on freeinvoice.cc for filament, power and machine time. If you want a real price for having us print it, upload the STL for an instant quote instead.

Why these run in your browser

Most free 3D file tools online are upload-and-wait: your model goes to someone else's server, sits in a queue, and comes back — which is why they cap file sizes, meter usage or want an account. These do the work as JavaScript inside your own tab instead. Your file is read from disk into memory on your device, converted there, and handed straight back.

That means nothing to install, nothing to queue for, no charge that scales with file size, and a commercial model or client's design never leaves your machine. The trade-off is your device's memory: files up to about 50 MB are comfortable on a laptop and rather less on an older phone. If you hit that ceiling, or the geometry needs repairing rather than converting, send it over for a manual quote and we will deal with it at our end.

STL, OBJ, 3MF — which to use

STL is the old standard: a bare list of triangles, no colour, no units, no separate objects, and no compression. It works everywhere, which is the only reason it persists. 3MF is its modern replacement — a compressed package that keeps each vertex once, records real millimetre units, and can hold several named objects with their own colours. The same model is typically a fifth of the size. OBJ comes from the 3D art world and shows up from Blender and scanning apps; most slicers will not open it at all.

In practice: print from 3MF where you can, convert OBJ to 3MF or STL before slicing, and keep STL only for tools that accept nothing else.

Common questions

Are these 3D printing tools really free?: Yes. There is no account, no trial and no per-file charge. They cost us nothing to run because every one of them works inside your own browser rather than on a server, so there is no bill to pass on.
Do I need to upload my files?: No. Your model is read from your disk into the browser tab, processed on your own device, and handed straight back as a download. It never reaches our servers. We ask for an email only at the download step, after the work is already done.
Do they work on a phone?: Yes, though memory is the limit rather than the software. Files up to about 50 MB are comfortable on a laptop and rather less on an older phone. If you hit that ceiling, send the file over for a manual quote instead.
Which file formats do they support?: The converter reads STL in both binary and ASCII, OBJ and 3MF, and writes STL, 3MF, GLB and PLY. The model cutter takes any of those three and gives you back one 3MF per piece.

Free to use, no account needed. We ask for an email when you download so we can tell you when we add new tools — the work itself happens before that, on your device. Need something printed? Request a manual quote.

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Which tool do I need?

“My slicer won't open this file.”

Use the 3D file converter. It reads STL (binary or ASCII), OBJ and 3MF, and writes any of those plus GLB and PLY. It also fixes the common case of a file with the wrong extension, because it identifies the format from the contents rather than the name.

“This model is 450 mm and my printer is 256 mm.”

Use the model cutter. It cuts the model into pieces that fit your bed and adds connector pins and matching sockets at each cut, so the printed pieces line up and glue back into the original.

“What does this print actually cost me?”

Use the 3D print cost calculator on freeinvoice.cc for filament, power and machine time. If you want a real price for having us print it, upload the STL for an instant quote instead.

Why these run in your browser

STL, OBJ, 3MF — which to use

In practice: print from 3MF where you can, convert OBJ to 3MF or STL before slicing, and keep STL only for tools that accept nothing else.

Common questions

Are these 3D printing tools really free?

Yes. There is no account, no trial and no per-file charge. They cost us nothing to run because every one of them works inside your own browser rather than on a server, so there is no bill to pass on.

Do I need to upload my files?

No. Your model is read from your disk into the browser tab, processed on your own device, and handed straight back as a download. It never reaches our servers. We ask for an email only at the download step, after the work is already done.

Do they work on a phone?

Yes, though memory is the limit rather than the software. Files up to about 50 MB are comfortable on a laptop and rather less on an older phone. If you hit that ceiling, send the file over for a manual quote instead.

Which file formats do they support?

The converter reads STL in both binary and ASCII, OBJ and 3MF, and writes STL, 3MF, GLB and PLY. The model cutter takes any of those three and gives you back one 3MF per piece.