But how to make the shape? I saw there are a lot of such things using pepakura techniques, but that assumes 0 thickness. So I wrote a Python script for Blender to compute the faces. (it fails a some edge-cases, but those can be fixed with a rotary tool)

I also had to decide how to attach things. Plan A was to create 3D printed parts that are screwed into at each vertex. However figuring out the geometry of that was more difficult, and I had a different idea to make small "brackets" that connect the edges. Which worked great for wood and poorly for acrylic.