Cage adjustment or help please

[Kaoticness]

My Rabbit went to the vet today due to his toenail ripping off. He has a habit of jumping to the top, half cage, and then jumping down, which obviously led to him ripping the toenail off. I need adjustments or what to do to prevent him from getting possibly more injured if he keep his behavior up, he is in an Amazon basic dog pen I think it’s between 36 and 42 inches I don’t remember the exact height I don’t have a problem if I have to buy him something bigger I just need to figure out what can I do to make him stop before he hurts himself even more

 

[Preitler]

Maybe putting a cardboard box on top and fix it there with cable ties or such? You could cut off most of the top half and fix a ramp to get up and down?