The faces and core for a model demonstrating one possible mechanism for the center of a Rubik's cube.
It would be far cheaper to just buy a Rubik's cube and disassemble it, but in case you want to buy one of these, you will also need:
Edges:
https://shpws.me/T4WQ
Corners:
https://shpws.me/T4WR
To fasten the faces onto the core, you will also need six M2 nuts and bolts (threads at least 10mm long).