Our 5x3 grid (minus one corner) piggie paradise. To protect them from drafts along the floor, we elevated the cage itself, and got nifty storage space underneath it.
The ramp is covered with coarse table cloths that are cheap and can be chucked away when they get too peed on.
The piggies have one small house and one large enough to fit all four (but they don't feel like sharing it anyway).
The clear coroplast? Was the only one I could get here in Norway, and what a hassle... Not to mention I had to go to Sweden to buy the cubes! But the result was worth it and the little piggie herd (we have four) seem to be very pleased with their spacious home.