I made this Tower of Pi based on the original Tower: http://www.thingiverse.com/thing:271769.
As regular fonts don't print very well standing upright, i created a font, which has no horizontal elements (numbers only). Therefore it can be printed standing upright from bottom to top without support and without getting rests of filament stuck between the numbers from parts being "printed in the air". The font was created using a free tool and can be found here, free to use: http://fontstruct.com/fontstructions/show/1122708
The fins above and under the numbers ensure the safe connection to the guiding helix.
The stl-file is not manifold (according to repetier-host), but will print beautifully.
Fun fact: When you read the first 3 digits from the inside/backside, you can read the word "PIE" ;-)
towerOfPi2.stl | 4.5MB |