There seem to be a lot of search results answering the question of how to increase wall thickness, but how can I decrease wall thickness? I have an STL model of a mechanical keyboard key where the outside dimensions are correct, but the walls are slightly too thick so the key gets stuck in the down position. I'd like to shave some of the thickness off of the inside of the walls to better match the original key I'm replacing, while leaving the rest of the model dimensions as-is. How can I go about doing this? I consider myself technical in general, though I'm a novice at 3d modeling software.

  • $\begingroup$ Welcome to 3dPrinting.SE! $\endgroup$ Jan 3, 2019 at 12:56
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    $\begingroup$ Be careful with nomenclature: When you open your slicing tools (e.g. slic3r or Cura), the word "Wall thickness" refers to how thick of a solid layer is created before the slicing software switches to designated infill for the object. In your case, it sounds like what you want to do is change the dimensions of the part you're designing, i.e. total part thickness. $\endgroup$ Jan 3, 2019 at 16:22
  • $\begingroup$ @CarlWitthoft It's basically a 5-walled cube, where the bottom is open and the inside is hollow. It's the 4 side walls that I want to decrease the thickness of, leaving the overall outer dimensions in place. So yes, I do mean the thickness of the solid walls, though not overall. Does that make sense? $\endgroup$ Jan 3, 2019 at 19:56

1 Answer 1


The process is rather simple:

  • import your model into either a modeling software (e.g. Blender et al.) or a CAD-program (e.g. fusion360, Design Spark Mechanical et al.) that can import and export STL.
    • if needed, convert the STL into a useable model with your chosen program's functions or switch to edit mode.
  • select inner walls and extrude them the desired amount.
  • export as STL again.

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