For the past year or so I have been cutting my templates from 3/32 ply and then gluing .020 music wire on the edge. The stainless wire I use on the bow glides over the templates really well. I have not gotten into lightening the foam as much as Bob. As far as cut outs for servo mounts and such I use my dremel router with a dry wall bit. before sheeting I sand the cores with 320 and vacuum clean. They really need to be as dust free as you can get them. Any flaws can be filled with light weight spackle. For attaching the skins I use epoxy with a touch of cabosil added and vacuum bag them. if added strength is needed in some areas, a strip of 2 oz cloth between the sheeting and foam does the job.