Free tool to lengthen/shorten a printed part's STL without re-modeling it — feedback wanted
I haven't had the time to really sit down and learn 3D modeling yet. I print stuff other people designed, and every once in a while I hit the same wall: a part is close to what I need but not quite — usually a bit too short or too long somewhere — and I only have the STL, not the original CAD file. Scaling the whole thing isn't really an option, it stretches everything and round holes turn oval.
Since I hadn't gotten around to learning the proper way to do this, I put together a small tool that just does the one thing I needed at the time: pick a plane through the part, and insert or remove a slice of material there. Everything else in the mesh — holes, walls, rounded edges — stays untouched, since it's not scaling anything, just cutting and splicing material in or out at that one plane.
SkipCAD, if anyone wants to try it. It's a rough prototype, put together to solve my own specific problem, so I'm sure it breaks on STLs I haven't run into yet. If you've got a part that needs this kind of tweak, I'd like to know if it actually works for you or where it falls over. Contact link's in the sidebar.
Edit: renamed to SkipCAD (unrelated naming collision with an existing filament brand — sorry to anyone who hit a dead link because of it, should be fixed now: skipcad.com). Also shipped a couple of things people flagged here — typing decimal values into the length field actually works now, and you can chain multiple cuts without re-exporting/re-importing the file each time. Thanks for the feedback so far, keep it coming.
Edit 2: Didn't expect the amount of feedback on my last post — genuinely appreciate everyone who tried it, reported bugs, or just left a comment. One request came up a few times, so I built it.
Cutting behind an overhang on a C-shaped part (or a leg of a U-shaped bracket) and only extending/shortening one side, without dragging the rest of the piece along with it.
The short version of why this was hard: normally the tool cuts a piece with a flat plane and moves everything on one side of it together, as a solid block. If the two arms of a C or the two legs of a U don't actually touch at the cut, moving "everything" means dragging both together — not what you want.
What changed: it now checks whether the cut plane is going through a spot where the piece is already physically split into separate pieces. If it is, it highlights each part and you can click to leave one alone — only the parts still selected get extended or shortened.