Dashboard Touch.  

Anil did a nice job building and publishing a fun project: a DIY Touch ID-like fingerprint sensor that can unlock your Mac, called Dashboard Touch. I liked what he wrote about making it: “Nearly every task in this project has had me stretching to do things that I’m pretty bad at, from firmware coding to security review to detailed carpentry to video editing.” Working at the edge of your capabilities across different skills is the most uncomfortable and satisfying kind of project.