Cardboard boxes! Cut entrance and exit holes much more fun than the bunny treats that arrive in them.
I have a little Nethie who looks just like these. He gets "in the box" and then 'walks' it (like a tortoise shell on his back) to the side of their run on the lawn, then jumps on top of it and jumps out of the run.
But he's 'just a rabbit '!!!
BTW these 2 cuties need to go on the Nethie thread.