As a conventional PC case would be far too thick, I needed to find something I could mount the machine in so that it would fit within the frame. Luckily a folding wallpaper pasting table was perfect for the job - and also on sale!
After cutting the pasting table to be the same size as the bottom panel of the frame, I set about fitting the PC into it. As the pc was going to be dropped inside the wall, all the fans had holes cut into the lid so that air could still circulate. I also fitted a large wireless aerial and made sure all the connections ran up to what would be the top edge of the case.