All of my boys LOVE cardboard-my robos love egg boxes and recently i made a play 'thing' from a yoghurt pot crate that yoghurts are stacked in at the supermarket, that they love climbing on and popping in and out the cut outs.
My syrian one day decided to move out of his hamster igloo plastic house, and camp out at the bottom of the tube in the cage, and i read that they arent greatly ventilated and therefore he might've been getting a little hot in there, so my fiance came up with the great idea of using an empty tissue box as a house for him-not a mansize box, one of those cosmetic facial tissue boxes that come in cubes. After a clean out, i popped it in for him, filled with bedding and some treats as a bribe and he has now moved into the tissue box quite happily, and it really is perfect for him!
Oh and they all adore the middle of toilet rolls, they also like it if I leave the last little bit on the roll for them to shred up and make their own bedding
