I have been playing around with mandolin tuners. The advantage is that you get 4 in a nice neat line 25mm apart (about an inch) and the knobs can be flipped left to right without much trouble while most single tuners ned 1 1/4 inch spacing. So how to fit them.
First up I took it apart and drew a freehand copy of the 70s Japanese copy of a 60s Fender headstock. Clamping the backing plate to the front in almost exactly the position I wanted it except it is a little bit to the left of where it should be. I started the holes using my 5mm brad point bit through the holes the posts go through.
Well thought out design.