86T pulley for GT2 belt is a slip fit over the knob on one particular 4" rotary table (ebay item 170729688086). This particular table has a 72:1 reduction worm drive. It might be better to have made this 85 teeth, with a 17 tooth driver on the stepper shaft pulley. That would give 85/17 = 5:1 reduction or overall 5*72 = 360, so one full turn of the stepper shaft would be exactly 1 degree on the rotary table. This pulley body is hollow to fit the handle, so flip the .STL file over 180 degrees before printing to avoid an overhang problem. The source OpenSCAD file is provided (but note, this one takes a long time to render, 8 minutes on my PC). It is derived from "drofarts" parametric pulley file, thing:16627 --- UPDATE: I added an 85-tooth version (that is the "bronze" color version in photos). The wall thickness is only 1.0 to 1.8 mm thick across the toothed part, but it seems to work so far. Here it is in motion: https://www.youtube.com/watch?v=65XTDXORBIs