My side pic didn't post. I'll try again today. I cut the centers with a CNC plasma, and drilled the bolt holes at work. A sheet of 3/8 steel ain't cheap, and I really think that the 50 bucks that some vendors are asking for the centers is not to much. I would order some before I made them again. I am using PVC lock rings that I also made using 16.5 forced sewer pipe rated for 165 psi ( it is an inch thick). The only down side is how much these things weigh.