Filament reel trackball [fits any brand]

Turn your old empty filament reel into a trackball toy for your cat! Tracks fit any filament reel size, just use the connector to join and hide any gaps. You can use any ball that's ~53-55mm large. A heavier ball seems to be more satisfying to slap around. 

Print the shaft, base and ball cap for a multi-tiered toy. It looks cool.