TUFF-R
Home Depot sells an insulation product called Tuff-R, locally in a 3/4" thickness where I am at. A look at the MSDS sheet reveals that it, too, is a type of polyisocyanurate foam board. Further, it's known that some builders of Tri-Magnums have used Tuff-R. I am rebuilding my canopy out of Tuff-R.
Foil Coatings
Tuff-R has foil coatings on both sides. I found out (the hard way) that the foil coating is different from one side to another, at least on the stuff I bought. On one side, the foil peels of easily. On the other side, however, completely the opposite. I would take this into account if using Tuff-R. I used a straight pin and tweezers to pick and peel off the difficult sides, several hours' work. Some users have reported using heat guns.
Flexibility
When one side is peeled of foil, the foam tends to curl a bit. When both sides of the foam are peeled off, the foam becomes very flexible, much more so than the 1" Trymer 2000 that I have. The challenge then becmes having enough rigidity to maintain the straighter shapes you want, which I did by using supports added in. I was pleased with its ability to curve easily. So far, sanding and glueing using solvent-based contact cement have all gone very well. Workability up to this point has been great.
Cost
Prices will vary according to region and retailer. For the sake of anyone doing research here is what I found out. Trymer 2000 (gray) was running about $35 per 4' X 8' X 1" thick sheet at Southwestern Insulation. Tuff-R ran me about $16 per 4' X 8' X 3/4" thick sheet at my local Home Depot.
