Summary

A ball with holes in it, with a bell inside. Useful for feline amusement.

Instructions

This is designed for PLA; PLA is glassy and the bell sounds nicely; if you try it with ABS let me know if it works!

I have printed this with a Replicator 2 with the default settings (15% infill, 3 layers, 0.1mm layer spacing). It also works with more layers (say, 5), which you might want to do if you want it more robust. The design has built-in supports so print it without supports or a raft. I have also printed it at both 100% and 75%. At the reduced size, the bell is higher-pitched. My cats seem to prefer the smaller size. Printing at even smaller sizes may not work due to clearances for the built-in support and the fact that the bell's shell is intentionally thin.

The supports are designed to keep the ball from rolling off the platform while it is being built, while keeping the base narrow. They are not actually attached except at some very small pins which will snap off easily. After building, just pull the ball out of the supports... it will probably happen naturally. Don't bother trying to remove it with a spatula.

Then you need an exacto knife or box cutter to free the bell and its clapper (another dense ball). These are held in place by four very small pins. Make sure you cut the clapper free and clean out the stubs of the pins on the bell before freeing the bell.

This thing is "mostly done" but I may make a few small tweaks later.

UPDATE: Original supports were too thick and apparently caused problems with ABS printing. I split up the supports more and cut them down to a 50% duty cycle. I also opened up the (very small) hole in the ball; before cutting the ball loose, drop in a little catnip or silvervine oil...

Bell Ball