Thank you all for your replies. I've spent part of the day reading about foamies. I even just did a q&d (quick and dirty) calc on the weight savings comparing a sq ft of foam build to the same using 1/8" ply skins. Impressive saivngs!
Maybe you can help me out. I'd like to read through/see photos of a basic foamie build but all I keep finding are these very large threads that seem to be somewhat experimental. Is there a simple tried and true method? It appears that there is: build foam walls, attach to floor. Add spars. glue on roof to foam walls. etc. Add TBII full strength, add canvas, watch canvas shrink, watch foam crack (oops). Coat with diluted TBII. Start on interior. Figure out how to keep the canvas full of glue from falling on your head, etc. But - I haven't been able to find the basic, generic build.
Oh, and I did read on a posting about building a foamie that the initial weight of the wall was 14 lb. After the addition of glue and canvas, the dry weight was 20, a little over a 40% increase. Does this sound about right? (The value was for canvas on one side of the wall only).