I wanted an extruder rotation indicator for my printer that would look like a simple gear, and this is the result. Before printing this, make sure first that you have an 8x3mm magnet and some superglue.
I designed this from scratch on FreeCAD and the design file is also available for download. So, if you want change things like the number or the size of the teeth it should be pretty straightforward.
Extrusion Width: 0.4mm
Top Solid Layers: 5
Bottom Solid Layers: 4
Nozzle Temperature: 235°C
Material: Das Filament Orange PETG