Parametric design: collar for 8mm smooth shaft, with option for one or more M3 setscrews. Updated design can be adjusted for any diameter shaft, setscrew size, and number of setscrews in the SCAD file.  You can get asymmetric by setting a non-integer number of setscrews.***Normally one setscrew is enough, and may be more secure. Two screws may allow the collar to pivot slightly on the screw points, but could be used with one longer cross bolt all the way through, if the shaft has a slot or cross-bore.***Currently adjusted to be quite close to nominal 8 mm so may need some cleanup / reaming to fit, and especially the M3 setscrew holes which come out a little D-shaped due to unsupported overhang.