Knowing the size of the base of the sim (8′ x 8′) I was able to do some math and figure out the size of the screen needed. There is a 7″ space behind the end of the rear windows, so the numbers come out to a circle that has a 128″ diameter for a 270 degree view using 3 projectors that are 90 degrees each. This tells me it’s a 64″ radius and that is key. Knowing that will allow me to use the ol’ nail, string and pencil to make a compass trick and draw out the curvature of the screen onto plywood, then add 4″ and draw the other line. I’ll cut out several of those to form the base of the circle and attach them together. I’ll use 2×4’s as the uprights and then cut the came pieces out for the top. Finally I’ll use 1/4″ or so mdf type material to make the screen. It gets painted satin white usually, which I may do regardless. But my intention is to get projector material/fabric and cover the entire inside surface with it, so that there are no lines from the construction.