Cat trees are an easy and fun thing to make, as you can utilize scrap wood and leftover materials to make something your feline friends will love. I live in a huge house with several cats, so I think I'll be making something like this soon. I'm especially digging the ones that make use of real branches for an organic look.
Cool use of real wood, and it lights up!
This one is a pretty cute idea...
Wow, this one is a serious cat kingdom.
Nice to have a hiding spot below.