I was going to by the rings from ringtraining.com but I checked myself. I always have a habit of jumping in and buying things at the beginning of an interest before judging whether I really need them. So I was thinking that I could make homemade rings and see how I like working out with them and if I do, I could always buy the real ones later. I was going to use the section of PVC pipe with a rope through itbut then I read instructions on how to make an entire ring with PVC.
You basically cut a 27" piece (approximately) of 1" PVC, fill it with sand (left over from when I made my sandbag), plug the ends with duct tape and then heat it in the oven for about 9 minutes at 350 degrees. It'll get soft enough to bend around a paint can or something similar and the sand keeps it from kinking. I screwed up the first pair because I don't know the difference between inside and outside diameter, apparently, and cut the pipe too short. Also, I didn't bend it well enough to be able to slip on the coupler. So the second time I used longer pipe and bent the ends around and dry fit the coupler while it was still warm and held it there until it cooled. Then glue everything together and let it set for 24 hours.
I didn't get a perfect ring but they are about 8" inside diameter and they hold my weight (175 lbs) so far. I didn't have any adjustable straps but I'm sure I'll run across some eventually. Using the rope helps keep my knot tying skills keen. In the photo below I have them set-up in the dips position. To move to push-ups, I just unti them and the load goes to the outside ropes. I use a lineman's knot in the middle of the rope to make a loop and can then secure the rings using that with that in a variety of positions. I think I'm going to put 2x4's on the ceiling for a place to do pull-ups and practice muscle-ups. The bar gets in the way for muscle ups.