Fire-puzzle by George W. Hart

This puzzle was originally designed by George W. Hart. I tried to design this in OpenSCAD, which I eventually succeeded in doing. I rounded the edges and corners of the tetrahedron for a better haptic. Thanks to @BikeCyclist the design is now much smoother.

https://www.georgehart.com/puzzles/fire-IPP-book.jpg

Print twice with support, preferably in different colors.

There are three files with different amounts of backlash.

What fascinates me about this puzzle is that it takes many people a few minutes to solve it, even though it consists of only two pieces, and those two pieces are completely the same.

I have created the model with OpenSCAD, rounded the edges and corners, and created multiple versions with different amounts of backlash.