You need a carboard box that will cover your screen. It should be just deep enough to hold
the rolls (cut it to size).
Then cut the bottom out leaving a small border for strength and for glueing the projection screen to.
My wife wouldn't surrender any old white T-shirts or old sheets to use as a projection screen so I
used tracing paper and glued it to the front - I think it worked quite well.
The new version of the pixalator turned out to be quite poor. The idea of shortening the loo rolls to make the image brighter meant that the projected image was no longer "pixalated" into the stone like image above but instead looked more like a blurry version of the original film. This was quite dissappointing but I now have a new idea to work on.
I might put an LCD screen and a used mini DVD player into a dedictated box. The box would be light shielded and the pixalator would be built permanently into the front. The aim would be to make the whole thing look like a deep picture frame with an on/off switch on the side. I'd then hang it up on a wall in a dark corner and just have a power lead going to it. It would obviously need ventilation holes to keep everything cool. I'll try and get the bits cheap on ebay or freecycle.