What is in your ratty's playpen?

I made the girls a new playpen out of coroplast and they love it!!

I'm trying to think of some new fun things I can put in there for them. So far the best "thing" I've put in is my daughter they climb all over her and seem to have a lot of fun, while she watches tv on the iPad.
But she isn't always available for ratty playtime and other than a couple of tunnels, a house and their wheel there isn't much for them to do yet. The big blue thing in the first pic is a piece of their old playpen which I had in there initially just to make it smell a bit more familiar, but I've since tossed it because I couldn't get it clean. So now there is tons of space and I'd like to make it really fun for them but I need some ideas!

Looks great!

I make the play area surrounded by chloroplast large enough for me to get into too (it is now half the room LOL)
I would suggest fisher price and little tykes toys such as the parking garages
a box with two side entrances and an entrance on the top & filled with crumpled paper ...... pvc drainage pipes cut to 15 in lengths and connected with T and elbow connectors

old pics for example: http://www.ratshackforum.com/forum/showthread.php?t=32723&highlight=playpen

That looks great! My guys have their own room but I block off certain areas with coroplast.