Multicube (functional clone)

This is a functional clone of Greg's Multicube produced by Yuxin. I never printed this particular puzzle as I already have one mass produced. I just wanted to prectice in designing puzzles like this. So please let me know how does it work.

Original CAD document is here: https://cad.onshape.com/documents/8d39382def9ea2b727dfd829/w/807544f66a276a0647e1ef04/e/b30bc048b070826f52129c17

Printing recommendations:
- 0.3 or 0.4 mm nozzle
- 0.1 mm layer high (0.2 mm should work as well, but higher layer height will lead to uneven surface)
- 2-3 perimeters, 10-20% infill

There are 2 versions of parts: split and non-split. Non-split ones are pars as is. You will probably need supports to print them. Split version does not require support, but each part is printed as 2 halves that need to be glued together (I would use acethone for ABS, and dichormethane for PLA and PETG)

Here is number of parts needed:
- 1 core
- 6 inner centers
- 6 outer centers
- 8 inner cores
- 8 outer corne