How hard is the octagon part to make and install?
The octagon came as a kit of eight wedges with most of the decking pre-installed. The hard part was getting precise placement of the support posts so that two adjacent wedges would sit squarely on the posts. Cutting off the posts also had to be done pretty precisely to keep everything level. Once the wedges were placed on the posts, I aligned them and bolted them together. I think the wedges would be pretty simple to make if you don't want to purchase a kit. You would probably want to build it on a flat concrete pad and then separate the sections for installation.
