housing for special needs bun

hi all:wave:
as some of you may know i am now the proud owner of kiri's buns (well soon to be). I was thinking of building a playhouse for them with a avairy attached same as my other buns have. The prob is that maddie has arthritis and cannot get up or down ramps so i was wondering how i could make their living space interesting without being able to build any upper levels. Any ideas?

lots of tunnels and crevices for them to go in to. Maybe build a cardboard maze for them once in a while.

Mine love going into tiny spaces (one of them managed to go in to a gap that we said she'd never be able to get in to, then turn back on herself and come back out!) so we put boxes with a small gap next to a wall so that they can creep in and they really like crawling underneath an old hutch we put in their run but I'm not sure if that's possible with the arthritis.