I'm forming the base of the canopy hatch. To allow for some clearance I have heat formed some 1mm styrene and double sided taped it to the fuselage hatch cut out. I have some 4mm threaded rod to hold it in position while the epoxy cures. I use a layer of 200gm glass and a mixture of epoxy and microfibres to form the surface. I'm relying on the release agent to get it off.