Bwahahaha, our evil conspiracy has borne fruit. He is addicted. [>:]

The foam is trade-named "Depron," available in 12" x 40" sheets from www.depronusa.com and other suppliers. 6mm (1/4 inch) thick is the most common material for outdoor flyers. Indoor foamies and light bipes like the Tensor are made of 2mm or 3mm.

For quick-and-dirty prototype work, you can go to one of the big-box supply stores (Lowe's, Home Depot) and buy 1/4" thick "fan fold" insulating foam. It's cheap, but a little heavier than Depron. Glue it together with Z-RC56 (air-dry, vinyl-based white glue) or foam-safe medium CA and foam-safe accelerator. Good hinges can be made using 3M Blenderm sticky tape, applied to beveled edges using the old "Monokote hinge" technique.

The main wing spar is usually 3/16" hollow CF tube. I get mine from www.darrolcady.com .

Plenty more hints & kinks if you browse this forum, or feel free to ask. Misery loves company!