This model is designed as a sanding head for a dremel. It requires a 1/8"in dremel shank that adapts to an M6 screw, and an M6 screw to be glued to the sanding head to connect it to the dremel. Because its another project I leverage heavily the screw holes to connected the front and baseplates together are compatible with these: https://thangs.com/designer/Keep%20Making/3d-model/9%20mm%20Small%20Thread%2C%20Flat%20Head%2C%20T-Bolt-973894
It also uses a 2.5 diameter Inch 1/12" thick glass insert to create a flat surface for the sand paper.