...Kuranda cat tower...make my own from PVC pipes and material...maybe a side attachment of wide pipe wrapped in rope for scratching
This material and pipe were designed to transport water, as it cannot wear out over time like rusting metal can. PVC is also structurally very strong.
These designs utilize tubes and cut-outs as the bases and structures of these products which links into a strong structure to put weight on. I like these designs because they look comfortable to sit on, and look simple in its assembly.