The 32 Crystallographic Point Groups ("simple" set)

This set is geared towards classroom teaching. It is meant to be as instructional and simple to understand as possible, while being easily printable. It is not designed to pose much of a challenge in any kind of exercise.

Look for the file “solution.stl” in the "extra files" folder for point-group-to-model assignment. That file is not meant for printing. There's also a file with tags/labels in case you want to attach them to the models or create a collection, student exercise etc.

I designed several variants, both for multicolor and singlecolor printers (see image for examples, sample_print.3mf contains 4/mmm in all shown styles). The blocks are relatively big (to be shown around the classroom, height = 5 cm). You can downscale all variants without symmetry elements to 75% or 50% (see pictures). 75% also works well with symmetry elements, any smaller would most likely require a smaller nozzle (or a redesign with bigger symmetry elements). This should be an easy print, at least in single color.

Notes: There are a few cases where rotoinversion axes coincide with rotation axes (e.g. in 4/mmm).  I'm not depicting these and just use the main axis from the symbol, like it's done in the International Tables of Crystallography. The models also do not indicate the inversion centers at all (i.e. no dots on axes passing through them). Inversion centers are the only detail where I deviate from Table 3.2.3.2 in the International Tables of Crystallography (anyway they should be easy enough to spot). The only remaining “dotted” axis in the models is 3bar, because that is its official symbol. Of course all this only applies if you print the variant with indicated symmetry elements. Maybe at a later time I'll design a version exactly like in the International Tables (i.e. with inversion centers indicated on the top&bottom), but currently I think it would just confuse students more.

Check out my other symmetry models:

Minimal set
Didactic set
(Pseudo-)Minerals set
Molecules set
Real Life Set
Spheres (Pac-Man)
Spheres (rings)
Teddys

Printing hints:

The files group the models by crystal system, so you don't have to add the multicolor parts to every single model. I arranged them with 90° angles, so you can place multiple crystal systems in a square for smaller printers (i.e. hexagonal+tetragonal+orthorhombic+monoclinic and cubic+trigonal+triclinic).
All the "solid" models are straightforward and print just fine with default settings. You will need supports (organic!) for all models in the "hollow" style with unfilled arrows. If you print the arrows solid with a different color, only the hollow cubic models need supports. You definitely need to increase branch diameter, or the longer supports will most likely break off near the end. Based on my test prints I suggest 4 mm branch diameter for 100% scale, 3 mm for 75% and 2 mm (default) for 50%. The hollow cubic models are the only ones that can be a problem to print. I had 1 in 5 fail randomly due to supports breaking off, so consider printing them separately. Despite PrusaSlicer warnings, the chamfered lower edges require no supports (change overhang threshold to 40° to prevent the slicer from generating them). Have long needle-nose pliers & a screwdriver ready for support removal if you print hollow cubic models, the insides of the cubes are hard to reach!