The buck is made of MDF with a wood filler top coat to give a smooth finish (aluminium epoxy resin would have been better). I used 2mm thick acrylic sheet heated to about 185 degrees for 50 seconds before applying the vacuum and then raising the buck into the heated acrylic sheet. Finish is very good just a couple of imperfections which will be sorted out before the final lenses are made which will be 3mm thick.
