This is a rather large extruder visualizer, but it still works pretty well unless the printer is doing some fast extrude-retract switches and then it kind of flops around, but that's okay. This is mostly for fun and to help me and my boys understand how the extruder does what it does.
As with all extruder visualizers, you will need to get yourself a small neodymium magnets, about 3/8" diameter should do the trick, I think. I found mine as a pack of 10 at Home Depot in the fasteners aisle.
I printed mine using TIANSE Violet/Blueviolet and Hatchbox White, both PLA.