It uses 16 x 5.5mm ball bearings and printed bearing parts to achieve smooth rolling action.

2cm thick PVC pipes are used as the feet, cut them as long as needed or print something that fits.

Bearings need decent but not perfect tolerances. Use Random Seam positions for them and roller.

STLs are oriented for printing, Roller requires supports probably. nothing else does probably.

STEP provided for fun.

Walls? Who cares
Infill? Roll a D100
Layer Height? 0.1mm for crowns and bearing surfaces probably