I designed this for my nephew, who had a few issues with wayward dice during our first Dungeons and Dragons gaming session. The tray in front is designed to fit a standard set of d20 gaming dice.

This one definitely requires a heated bed (110 C recommended) to print properly. I'm still struggling to avoid curling at the corners, but the Aqua Net trick helped. http://www.thingiverse.com/thing:28787. The curling is only happening toward the end of the print, so I bet lowered exterior walls would help.

Printed at 0.3mm layers.