C&C I have a C&C but would like to build UP

I have a C&C but it is only one level. I don't have much more "floor room" in my living room and don't really want to move them out of there - that is mostly where we are when we aren't at work and they enjoy the interactions with my husband and I. Plus my other living room would have them in a picture window and I don't want to do THAT!

I think I'd like to add space by building UP for them. I see some really great pens (C&C ones usually) with the second floor and a ramp, my question - where in the world do you get something like that for on a C&C? Is it something you have to order, because our local pet shops don't have anything like that that doesn't come in a cage (and I think they would be too small anyway).

I'm just looking for some ideas and suggestions. I only have two piglets (spoiled little things) and they love their pen, they do laps, wheek and popcorn at me - especially after I change things around and give them new toys or new/different beds or special food. I just would love to give them a little extra room, make it a two floor palace, instead of a rancher.

The other question - is there something you put up top? Like the kitchen or the liter pan or just a play area?

Thanks so much for your ideas!