I have an old brick and plaster internal cottage wall. It doesn't seem too bad for smoothness but there is some heavily embossed anaglypta paper on there.
I'm thinking of cutting the required rectagular size out of the existing wallpaper and replacing it with a smooth paper, perhaps lining paper, then painting the screen area with some appropriate paint.
I'm not a home cinema geek. I bought my used projector for 20 quid from a local website. This I mention just to give some context to my expected cost level.
Any helpfull hints and tips would be most appreciated.