Pulley with 42 teeth for GT2 timing belt (6mm wide, 2 mm teeth) with fins that lock into the holes in one particular 80 mm inline skate wheel. This allows use as a drive wheel on a robot. The pulley bore allows a standard 608 skate bearing to fit through it. The fins look overhanging but this .STL file printed out OK without support (PLA on UM2 printer). OpenSCAD file provided so you might modify it to fit other types of wheels and hubs. The pulley itself is taken from droftarts' pulley.