The Cavy Cave is an idea developed jointly with Sally of Pampered Piggies. Originally made from twin-wall kraft sacks, the Mark II is made from card and kraft flour bags using a design which is more resistant to squashing.
It comes flat packed and consists of two flour sacks and 2 pieces of pre-cut A4 card. Not rocket science I know, but it is a simple and effective design which can be used as a toy for rabbits and chinchillas by stuffing it with hay that has a treat hidden in the centre.