WarrenP: I just went through your theater build--very clever for your screen. It looks very light and appears to store quite easily.
Right now, my screen is a very heavy canvas stretched between two very heavy steel poles that are attached to my backyard fence, then stretched taut with guide-lines (this picture is actually bit outdated, because I now use bungee balls along the bottom to tighten the screen up even more.
But man is the screen heavy, and very difficult to do by myself.
I am toying with an idea to use 4x8 sheets of foam insulation from Home Depot ($13 a sheet)--it's pretty dense foam with sheeting on each side (one side is silvery, but I think would cause some hotspotting because of its sheen). But anyway, it's pretty stable for foam sheets, and if I could figure out an easy and light way to frame it, I could easily make the screen 4 of these sheets side by side (they could easily be paintable with a primer for the screen material). There would be a seam between the four panel, but I think I could probably minimize that somehow (tape over the seam???)
I have noticed, however, that imperfections in the screen rarely show up on the movie at fully dark. My screen right now is heavily wrinkled and stained and none of this shows up during a movie. I wonder if any seams would...?
One other idea--instead of taping the seams, how about a cloth flap that is adhered to one of the panel and then lies flat against the other panel covering the seam (or use velcro??)
But anyway, WarrenP--since these are 4x8 sheets, I don't think you could use them for 23.5x10...But you could easily do 19x8 (use 5 panels, and even paint a 1 foot black border on the left and right...)