What does the dot matrix do? I'm not being sarcastic, I'm just wondering what the reasoning behind it would be.
The price my wife had for 3mm sintra was really good. I'm getting samples tonight, plus some scrap vinyl rolls for texting. It maybe that I can use a lo-tac spray adhesive on the 3mm, and stick it straight to the paneling, and that would remove the need to build a dedicated frame, plus it's half as heavy, so there would be less stress on the wall.
One other thing I have seen is tradeshow media. Normally it is a thin white polyester film. It's highly reflective, and thin like 1 mil thin. But that's not the interesting thing. This media is normally created in two pieces. A silvered backer (a thicker polyester film) is applied to give the front media some needed rigidity. The backer is very reminiscent of the high gain screens (excuse my lack of technical terminology) that seem to have reflective beads adhered to the surface. The surface is even, smooth, and slightly reflective. I will test how it works.
The good news is that most of these media rolls come in sizes up to 80" wide, and 100 feet long. Something in this industry will yield an acceptable picture, I am sure.
Now the downside will be that over time, there would be some yellowing...but it would be minimal. Your cost per square foot would be so low, you could just cut a new piece off your roll every two years. (I estimate cost per roll to be less than $150.)
Something to think about.