Dodecahedron, created from 12 separate pentagon volumes. Each pentagonal face is circumscribed by a 10cm circle.
I've liked the concept of creating many small repetitious things that assemble into something larger: This is my first attempt at that. Modeled in Autodesk Fusion 360.

Print 12 pentagons, and zip-tie together. The zippy holes are 3mmx2mm.
Printed on Makerbot Replicator (1) , "Low" quality settings in Makerware" (done quickly as a test), modified below:

• 300 micron layer resolution.
• 5% infill, 2 shells.
• Blue PLA printed @ 220 deg, HBP off.
• Printed on glass, covered with blue painters tape.
• You will need 30 zippies.
  Based on those settings, each pentagon took 30 minutes to print, so a total print time of 6 hours. I was able to get two printed per plate, laying flat (the uploaded stl appears to have them on-end).
  If you stacked them straight up, or over at an angle as defined by their bevel you could probably get many more, but the overall surface quality would probably suffer.