I wanted to create my own guitar string winder.
NOTE: the models are based on the size of the guitar showed, that is a 3/4 guitar from gear4music. Normal guitars should have bigger keys.
UPDATE 2015/08/10 - I added a version 2 with a reduced length of the crank. Based on my printed version 1 I also reduced the dimensions of the key and the clearance of the hexagonal connection.
Print it, then mount and fix the exagonal pin in the hole with superglue.