My daughter broke her piggy bank. I plan to print her a new one when I get my replicator. Holes sized for the american quarter dollar coin, I don't know if there's anyone out there with bigger currency, but I hope not.
It's mostly hollow with 3mm walls and a plug on the bottom for the extract of coins. There's some bad geometry and despite running it through cloud.netfab Blender still reports lots of little non-manifold glitches, too many to fix by hand. Hopefully it'll still print solid.