I use foamboard for the 80cm x 80cm x 20cm case and a lee filter “Heavy Frost” as a diffuser, inspired by http://jasoneppink.com/pixelator/,
Here is the final video – it’s basically a Space Invader generator – it will display a (more or less) random Invader head – inspired by “Space Invaders“:
I’m very sorry for the flickering – but its just visible by cam!
Kill ze Invaders!!
Here are some images from the build process: