It's an icosahedron! I made this for a friend of mine, and I thought I might as well share. I don't think there's an icosahedron that's hollow already up here.I'll upload my source file too. This was a fun object to model, because it can be constructed with three perpendicular golden rectangles.I sliced mine at 50% scale, and with 0.4 mm layers the walls ended up being 3 extrusions thick, which was just about right. Of course, the top will need to be bridged, so make sure you've got your temperature and feed rate settings calibrated or it may droop!