I used plywood as I have loads of off cuts in the shed. MDF would be loads better.
Yeah I think I'm going to make it so the gaps along the bottom edge and by the right shoulder match. The problem in the top right is there's not a lot of space to play with between the switch cavity and the edge of the template. There's probably just enough room for a screw. So I can make it bigger but not really any small in that area.
The original dlx tele is a bit of an odd shape - especially around the neck.