continuing my development on Youmagine. https://www.youmagine.com/designs/napier-s-bones The reason i am stopping development is Makerbot (the owner of thingiverse) has begun applying for patents for works done by the opensource printing community. This is theft of intellectual properties. I will leave this file up, but all future developments will be done elsewhere. http://www.openbeamusa.com/blog/2014/5/22/stay-classy-makerbot Napier's bones are a mechanical calculator that helps students relate multiplication of single digit numbers to simple addition and multiplication table. http://en.wikipedia.org/wiki/Napier's_bones