Pi day came and went this year, and I created this just in time.
Prints fine with Cura. Created originally in sketchup, and then saved out as stl from Cura. I scaled it 3x and saved it out, so I think this will print about 23mm wide, as is, but verify of course.
Pictures in black are abs, looks better in person than in photo. Gray PLA looked great also, as would other colors. PLA prints with less hassle on my Prusa. Ignore the stray triangles in the thingiview, it prints great, nothing needs to be cut away (cura 15.02.1).
Pi is approximately 3.1415
Wikipedia entry for Pi: https://en.wikipedia.org/wiki/Pi
Pi day: http://www.piday.org/