Want a nifty container to store small things in like coins, razor blades, screws, candy, etc ?  This is a 10 sided container that you can print the top and bottom in different colors to get a nice contrast.  It works well in PLA.  Print both of them with the flat side down.  I would recommend slowing down the perimeter layers of your print to around 25-35 mm/s because of all the corners the extruder head has to turn.  The faster you go, the more interference you will have on the corners when the two parts mate together.  The ones in the pictures were done at 72 mm/s for all internal layers and 30 mm/s on the perimeters and they fit together nicely with no interference.