Lorie the one in the review is modular and made of heavy cardboard tubes and plastic connectors and cloth/canvas hammocks. What I like best about it besides it being easy to move around, is when a cat scratches the post to the point of shredding, you just pop off the leg of the condo, order a new one for just a few dollars and you have a new condo again. It's pretty nifty!
Looks like Hermoine did a good job building her first homemade cat tree. They are not that easy to put together, and she did it all by herself too!
The important thing is just to give the cat height off the floor Hermoine, if you can't build a second level, don't worry about it. The cat will still feel secure. It doesn't look like your homemade one will tip- so good job!