Fender3x, I totally agree with you. The shim is basically a test piece for seeing if it would work really, the neck is 3.5mm thinner than the original and the ply being 3mm was a question of it being, was it too thin ? Then of course clearing the strings for the fret heights then realising the nut slot had been previously tampered with, being that the nut was sitting in way too deep, then comparing it with other nuts showed that the nut itself was ok but the nut slot also had to be shimmed. So the experiment is successful, I can now move on to improve on it and will be changing the neck shim to a hardwood as at the moment it is only a pine ply and I do expect it to expand and shrink with the different seasonal climates. Painting the shim in to match the body color is what I had in mind also.