It looks like you are using an ad blocker. That's okay. Who doesn't? But without advertising revenue, we can't keep making this site awesome. Click the link below for instructions on disabling adblock.
I just saw this video, it seems to me that it'd be pretty easy to make a rainbow rail, or some other stupid shape for a backyard setup. I guess it'd be harder with thicker pipes but you could use multiple skinny pipes if you like wide rails. Is there a reason people don't do this other than the effort required to make a support structure that fits a curved object and you probably wouldn't have enough speed for any kind up up rail? You could make S rails. https://www.newschoolers.com/videos/watch/965051/Easy-PVC-Pipe-Bending--How-To-DIY-