Here’s an image of Theodore’s recently renovated enclosure:
http://i.imgur.com/X86cU7C.jpg
Sadly, I don’t use C&C cubes so I won’t be able to help you there. D:
For flooring, I bought some laminate “hardwood” panels from LumberLiquidators.com for $15. They’re awesome! Super easy to clean and they look really nice if you see part of them. On top of those, I have a few cotton towels for softness. At the moment, I also have a big piece of cardboard at the pen entrance, because Theodore managed to spill his automatic waterer before I placed in the corner where he couldn’t do that anymore. That waterer is from PetMate and is the .75 gallon size. It isn’t pictured here because the pic was taken before I got it, but I do highly recommend them! When they’re full and placed in a corner, they’re basically impossible for bun to tip over.
I got his litterbox at a pet supply site, it’s originally intended for cats but of course works great for Theodore. Just above that, on the cage bars, I have a little basket zip tried to the bars. I put fresh hay in here for him to munch on, which works great.
I do not have any digging boxes for Theodore at the moment but I’m strongly considering making him one. There are some great tutorials for these on YouTube!
As for boredom busters, your general selection of toys does the trick, but more challenging things are good for the active bun. One thing I do with Theodore is take a paper towel or toilet paper roll, cit small holes in the sides and push in the ends, and put a few pellets inside. He loves to mess with this to get them out!