I'm off to the local Menards, (like Home Depot) in the next couple days.
On the phone at least, they have drywall in stock in the new(ish) widths of 4.5 feet, and they even have them in 12 foot lengths.
That 54 inch height stretches to 126.9 inches more or less for 2.35 ratio screens...so, this would be stupid easy to buy, slap on some Behr "Brilliant White" paint, and fool around with to see what the optimal size is for your scalar-lens CIH project, and not be upset with distortion from chromatic aberrations or pincushinging or zooming so large you see the pixels.
I'll be doing this to get an idea what I want before I invest in the fabric for an AT screen and build the frame for that.
Theoretically, I'm aware this is only 10 1/2 feet, but its so darn cheap and guaranteed flat, easy to paint and mount... even bend into a gradual curve, its hard not to pick this to be the size if the width of the room can accomodate it.
(Actually, the 4.5 foot width is a gd-send to me since the basement does have 9+ foot ceilings, two will leave me with just one horizontal seam... way less work eventually for the mudding etc....)
Alex