When we just adopted our cat, he was a whopping 10.5kg, and as a result, big and clumsy. We could not find any cat trees on the market which could hold a cat of his weight.
Since he is clumsy (for a cat), cat trees which required the agility and flexibility of a normal cat were out e.g. narrow platforms.
We wanted to encourage him to exercise more and to feel comfortable at home, so we decided to build something for him. We are not very adept with tools and this DIY cat climber hack requires absolutely no special tools – just the usual Allen key included in the flat pack.
We put cat food on the bottom most shelf as a means for storage, but also for added stability. While the blocky design of the cat climber makes it fairly stable, it still shakes a little when he jumps onto the highest level.
Since the post and shelves are made of untreated wood, and there were some splinters where the holes are, we sanded these parts to make sure our cat would not get hurt while rubbing against the posts.
Other things you can do would be to add a coat of varnish over the wood so it will be more durable and water resistant.