This was the first shape I'd ever designed for printing, which I made back on December 16th, 2009.
I wanted the center to be able to hold a small stack of nickels.
I haven't modified it to make it better, since it's mostly an historic piece for me now.
The pictures in the gallery show my first attempts to print it back in November of 2010, as well as my successful attempt this summer at Makerfaire NY 2013 when it occurred to me to try printing it again.
The original blog post describing my first attempts to print this is here:
Print the stl file. I've included the sketchup source file, the intermediate dae file during one attempt at conversion, the STL file to print, and a text file describing the steps that I took to make the shape in the first place in sketchup.
Careful placing nickels in the center - if the hole is too small they won't come out. :) Again, I'm not fixing it up because this piece is mainly an historic one for me and serves no real other useful purpose.