Updated a fun math shape generator

Back in 2013, “kakaroto” posted a nice curve generator to thingiverse.

However, it uses the assign function that is going to disappear from OpenSCAD, so I changed it to use normal variable assignment.

It’s fun to play with!


Created another variant to enable making molds by specifying a draft angle for the sides:

I had an interesting time finding software that can toolpath this shape, though. FreeCAD keeps crashing when I try. Kiri:moto runs indefinitely on Firefox, which is either better or worse than Chrome which quickly crashes the tab. Arjan van de Ven came to the rescue with open source software he wrote for his Shapeoko which finishes in about a minute. It currently has an interesting artifact that would be trivial to work around by extending the model and letting it cut a little bit of air.


Kiri:moto ran indefinitely because my model wasn’t manifold. I haven’t figured out how to make OpenSCAD generate a manifold here. The only obvious way would be basically equivalent to just writing code to write the STL directly. Prusa-slicer has made me lazy, I guess, by generally just making things work even when the model isn’t actually manifold.

I learned in the process more about how to fix non-manifold STLs in meshlab, and then Kiri:moto worked really well. It has a nice outline pass generator. It has clearly had a lot of time invested in it, and at this point I’m guessing that it will end up being my go-to for toolpathing STLs.

Here’s a top-down view with roughing op with ¼" flat mill as black lines, and outline op with ⅛" ball mill as pink lines, and three tabs in lavender:

It also has a simulation that draws a mesh. It’s not real-time but it shows the path.


It did a really nice job on my MDF prototype.

I think it’s about 15mm too narrow so I’ll scale up for the aluminum version. I also made the bars a little thicker but not much.