Copyleft Plans
From Qi-Hardware
All plans, designs and content (audio, video, image and text) that are required to construct 100% of the device should be licensed under a Creative Commons Attribution-ShareAlike 3.0 license.
pocket calculator
one obvious idea is to run gc (GNU calculator) on nano with some optical adaption to have a nice calculator, possibly with RPN or Hewlett-Packard 41C compatibility.