Adding a second level to non-C&C cage?

First of all.. man, these are some creative cages here! I wish I'd found this site before I was 90% complete with mine!

Okay, that aside, I have a HUGE (3' x 4') cage I made from the shell of an old dresser. It's very boring looking.. all my little one has right now is a single hidy house. After looking through this site, I got some great ideas to make his life more interesting for him while I try to find him a buddy, and also what would maximize space for when I finally DO find him that buddy. The cage is nearly 4' high... so I was thinking of adding another level in there. Has anyone had any experience making something like that, or just have any general ideas? Cubes wouldn't work very well, as there's not any place to connect them. Also.. I'm not exactly handy with building things. If you saw the way the cage looks right now when all I had to do was nail wire to a frame.. you'd understand what I mean.

Thanks in advance for any input!