first?
thingiverse
tried to bang this out as quickly as possible to win 9000 internet points ( http://www.makerbot.com/blog/2011/09/29/openscad-puzzle-challenge-how-would-you-make-this/) openscad's modular nature made this challenge pretty easy. make one shpere with 3 square through-holes, then repeat 3 times with a different radius.
Download Model from thingiverse
With this file you will be able to print first? with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on first?.