Custom Geometric Lattice

customizable lattice of space filling polyhedra AKA space-filling tessellation
AKA honeycomb
(see
http://mathworld.wolfram.com/Space-FillingPolyhedron.html,
https://en.wikipedia.org/wiki/Convex_uniform_honeycomb)
Similar to:
Christmas Something - https://www.thingiverse.com/thing:585147 (elongated dodecahedron)
ProFab Lattice Cube - https://www.thingiverse.com/thing:2522147 (truncated octahedron)
Octet-truss lattice - https://www.thingiverse.com/thing:2092513 (tetrahedron/octrahedron)
and several printer torture tests (cube)

slicing
- use skirt
- 100% infill
- if you select large x,y,z, fn on a complicated shape, the customizer may fail,
just try again with smaller values.
- unless you print a very small size, depending on the shape, you will
need supports - sometimes you can rotate the thing, for example, for cube,
you can rotate 45 degrees and only need support on the outside
- if you use supports, use a larger edge radius (1.5+ mm) or else
you will ha