nozzlefox

STLSTL

Merge STL files and cut holes

Join models into one solid, or cut holes, slots and shapes out of them, right in your browser.

  • Nothing uploaded
  • No sign-up
  • Free, no limits

Drop one or more STL, OBJ or 3MF files

or paste it, or pick it from your device

.stl · .obj · .3mf

  1. Drop one or more models
  2. Add shapes, move them, add or cut
  3. Download one solid STL

Good to know

How to merge STL files or cut a hole

  1. Drop one or more STL, OBJ or 3MF files. They're read on your device, not uploaded.
  2. Add shapes from the list: a cylinder starts as a hole straight through the middle, a cone as a countersink at the top, a box as a slot.
  3. Pick a piece and set it to Add or Cut away, then move, size and turn it. The red lines show the shapes being cut, even inside the model.
  4. Download the result: one solid STL or 3MF, ready to slice.

What you can do with it

  • Merge STL files into one solid: a base under a figure, a handle on a box, two halves that belong together. Where pieces overlap they're fused, so there are no hidden walls inside.
  • Add holes: screw holes, magnet pockets (a cylinder a little wider than the magnet, cut partway in), holes for cables or hanging.
  • Subtract one model from another: drop two files and set one to Cut away, to make a mould, a fitted case or a recess shaped like the part that goes in it.
  • Trim a model: cut away a box to flatten a bottom or remove a part you don't want.

Sizes that fit

Printed holes come out a little smaller than drawn. For a screw or a magnet to fit, make the hole 0.2 to 0.4 mm wider than the part, more for big holes; type the exact size by clicking the number beside a slider.

Merge or keep apart?

Merging makes one solid, which is what you want for printing in one colour. For a multi-colour print, or to keep objects you can move separately in the slicer, put the files in one 3MF with STL to 3MF instead. To cut a big model into parts that fit your bed, use Split STL.

A file with holes in its mesh is closed first, the way Repair STL does it, because only a closed solid can be combined.

Questions

How do I merge two STL files into one?

Drop both files into the tool on this page. Each stays where it was made; move them with the sliders if needed, then download. Overlapping parts are fused into one solid STL.

How do I add a hole to an STL?

Drop the STL and add a cylinder: it starts as a hole straight through the middle. Set its diameter, move it into place, and download the STL with the hole cut.

Can I subtract one STL from another?

Yes. Drop both files, pick the one to remove and set it to Cut away. The download is the first model with the second one's shape cut out.

Is it free and private?

Yes. It runs in your browser, the files never leave your device, and there's no sign-up or size limit beyond what your computer can handle.

Why does it say holes were closed first?

Joining and cutting only work on closed solids. If a file had gaps in its mesh, they were filled before combining, so the result is watertight.