My mother saved my favourite rattle for 30+ years from when I was 6 months old and recently gave it to our 6 month old baby boy. The dog promptly crunched it to plastic crumbs. It was a vintage Kiddicraft Clic Clac. I can't find it for sale anywhere so with enthusiasm I drew one up in OpenSCAD and printed it. He loves it. If the dog eats it again I shall laugh for 2 and a half hours while the next one prints out at 0.2mm with 25% infill. I'm sure it will work just fine with other settings, but the design does benefit from being a smooth print so even higher res would probably be good. The "knobble" inside snaps off easily once printed and slides around inside the main tube.