Summary This is a design based on the Extruder rotation vizualizer (https://www.thingiverse.com/thing:2759852) but not a "remix". UPDATE 6-1-2018: I changed the inner diameter to 8 mm. Mounting is accomplished with 2 magnets stacked to reach the extruder motor shaft. The inner diameter of the Trefoil is 8 mm which should fit the smaller neodymium magnets available from Home Depot and Lowe's without the need for glue. Print Settings Printer Brand: Prusa Printer: i3 MK2S Rafts: No Supports: No Resolution: .15 Infill: 70%