A bit out of sequence this post, but got some more progress on the Battery Compartment Cover Mould as well.
After milling out the profile in MDF, I've given the cut surface a spray with primer sealer to protect it a bit from moisture absorption.
a few coats and sanding then I'll paint it with a top coat and wax polish it ready to take a fibreglass panel off it.
Only needs to do one. :) ...one good one .