Luthiery specifically for me - it's a hobby currently and the thing I think about the most when I'm programming. The tooling and jig making aspect of woodworking is also very satisfying to my engineering tendencies.
I have to plug David Hurds "Left-brain lutherie" here! It's a physicist's attempt to demystify the building of guitar-family instruments, and in addition to providing a pretty in-depth look at the major components of an instrument's sound, provides many immediately practical tips on construction - for example, how to choose the proper soundhole size.
