A 3-in-1 extruder visualizer, you can selectively print the design that you prefer.

one with an auto-generated shape, one with crankarm, and one with my signature W.

the shape is generated using kangaroo 2 + rhino 7

print with brims, 3 walls, low infill for minimum moment of inertia

How to assemble:

use ⌀6*3mm magnetized-through-thickness neo magnet and EPOXY ADHESIVE (MUST) for best reliability (you don't want a magnet stuck dead on your E-motor shaft )

if you do not have epoxy adhesive, consider glue with resin, silica, or other heat-resistive adhesives; slot-in and friction-locking is not recommended as heat expansion and material creep can loosen the magnet;

dip a small amount of adhesive to the magnet surface, and carefully slide into the hole; please try not to dip the hole with glue since the adhesive could lock air bubble inside and leave cavity inside slot, which could lead to failure;

press the visualizer magnet side down onto clean surface to ensure flat mounting and eliminate wobbling during shaft rotation; clean any excessive adhesive;

keep pressing down until the adhesive starts to cure; leave clamped or pressed until fully cured;

to test the result, grab other magnets with comparable or stronger force, and try pulling the mounted magnet out; if no displacement is observed, then the mount is ready to go.

Maintenance:

take off the visualizer regularly to check magnetic force, cracks, abrasion, heat deformation and sign of loosen magnet; don't drop or overheat magnets since it will demagnetize and damage the magnets.