Perhaps the biggest riddle with making a homemade guitar that not only plays well, but plays in tune is the tuners themselves. It's a lot of fun to make the whole guitar completely homemade. Building a guitar with home made tuners is challenging but very rewarding. Over the years I have seen it done many ways, from eye bolts to homemade friction pins, zither style pins, homemade crank style tuners....just to name a few.
BUT, I think guitar builder John Toomey has found a way that not only looks cool but functions well. The metal plate on the head stock appears to be what gives the tuners stability when the bolt is tight against the brass plate, you can be sure it's not moving or slipping out of tune. How rad is that simple concept!
Check this out, the photo explains more than words. Add this to your "to do" list in the future and if you are ever without access to regular guitar tuners get out in the garage and see what you can create.
In this photo below he has made one of the tuners with a simple Phillips bolt head type with a small hole drilled thru it. It once again metal plate is the stopping point when you tighten the bottom bolt to provide stability, if it went strait into wood, the wood would not "lock" or seat the bolt well as the metal to metal does, and that is what really helps keep this guitar in tune. The possibilities are in in your work shop, look around and see what you can create!