This new design 2 storey play castle / shelter is ideal for your guinea pigs to play in. It's 18" wide x 10"deep and 10" high, with two 5" x 5" entrance holes on the bottom level with a open end on the upper level for your piggies to hop up on to. Its got no bottom which makes it easy to clean, just keep moving it around.(It’s not painted but most people have some spare paint left over in their shed or garage which would be suitable.)
 
Note: As these are made from plywood there may be some cosmetic marks on the ply but this doesn't affect the it.