Customizable tuning wrench for string instruments

A simple, fully customizable tuning wrench for string instruments with non-geared tuners (e.g., violins or, in our case, a lute-style ukulele). The author of [this very different design](http://www.thingiverse.com/thing:1711680) advises lining it with felt to protect the tuning pegs. (We used ABS which is a little softer than PLA and that should help a tiny amount.)

Your instrument is unlikely to have pegs the same size as ours, so you'll want to customize it for (a) hole dimensions, and (b) clearing other pegs.