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Hollow STL
Hollow out an STL for resin printing: set the wall thickness, add one or two drain holes and save the hollow model. It saves resin and weight. Free and online, and your model never leaves your browser.
How to hollow an STL for resin printing
- 1Drop an STL, 3MF, OBJ or PLY file in
- 2Set the wall thickness and the drain holes
- 3Click "Hollow", check the cut, save the hollow STL
- A hollow STL and the share of material saved.
What happens to your model
- Your model stays with you.It is opened and hollowed in your browser, on your own device. Nothing is uploaded.
- See the saving before you print.The volume after hollowing and the material saved in percent.
- Look inside first.A cut through the middle shows the walls and where the drain holes go.
What you can do
- Choose the wall thickness in millimetres, from 0.2 mm up. The numbers can be read as millimetres, centimetres or inches.
- Cut no hole, one or two, with a diameter you set, in the bottom, top or back of the model.
- Tick "Show a cut through the middle" to see the cavity in the 3D preview.
- Compare the volume and size before and after, with the material saved in percent.
- Save the result as a hollow STL, even when you started from a 3MF, OBJ or PLY file.
Good to know
- The model must be closed (watertight). If it is not, you are told to run the STL repair tool first.
- Up to 3000 triangles the walls are an exact inward offset. Bigger models get quick walls, which can be off where the model is thin, so check the cut.
- If the model is too thin for the wall you chose, nothing is hollowed. A drain hole that misses the inside is reported, so move it.
- Resin prints need at least one drain hole, or the trapped resin can crack the print.
Questions
How do I hollow an STL for resin printing?
Drop the file in, set the wall thickness, leave at least one drain hole and click "Hollow". Then save the hollow STL and slice it as usual.
Why do I need drain holes?
Liquid resin would stay inside a closed cavity. The holes let it flow out when you clean the print.
Which wall thickness should I pick?
That depends on the printer and the resin. The default is 2 mm, a common starting point. Thicker walls are stronger and save less.
Is my model uploaded anywhere?
No. Hollowing runs in your browser, in a background worker on your own device.