Looking for CAD files of basic crystal structures
You may find that OpenSCAD regular polyhedron library may serve your requirements.

From the linked site:
All polyhedra are centered at the origin and have an edge length of 1.
From the linked site:
Included polyhedra:
tetrahedron
octahedron
hexahedron
icosahedron
dodecahedron
cubeoctahedron
truncated_tetrahedron
snub_cube
rhombicuboctahedron
truncated_hexahedron
truncated_octahedron
icosidodecahedron
snub_dodecahedron
rhombicosidodecahedron
truncated_cuboctahedron
truncated_icosahedron
truncated_dodecahedron
truncated_icosidodecahedron

OpenSCAD is a reasonably easy &quot;description coding&quot; program at the base level. I suspect that for something such as this, it might not qualify for the easy reference.
My search also linked up a few Thingiverse entries, but they weren't as sophisticated as the above and may be a subset of the library link.