A simple shape for a replacement duffle coat toggle button. Easily customised in size. It has a flat part underneath to be possible to print, it could have a round underside if printed with supports but I chose not to as those themselves make marks in the surface. If you're picky about surface finish, it will need to be sanded down.

It needs a few top and shell layers to seal up the top surface. It depends a bit on nozzle size and layer height, I printed with 0.4mm nozzle, 0.1mm height, 3 shells and 4 top layers and it turned out pretty nice.