so for a physics project of mine i decided to build a sort of makeahift guitar out of wood that was laying around.

problem is that i don't know what i can do about the tuners, i don't have any extras and i was wondering if there was anything that i can use as replacements, or do i have to go out and get tuners?
You can use the classical guitar or lute concept and just make your own. You can also use a clamp at one end to hold the string, and then a bolt to tighten/tune it.