These are a great addition to a display. There are so many ways in which they can be used to enhance an animated display. Each one I made from 3/4" grey schedule 40 PVC pipe. There are 8 channels (or sections of lights) that each take up 2 feet of space on the pipe. So the pipes were cut on each end to leave about 6" of space that is not wrapped. This helps keep the lights off the ground a little. The pipe has one end that is larger to accept another pipe. There I joined the two pipes and then drilled a 1/8" hole all the way through to accept a cotter pin that helps keep the two pipes together. There is a lot of pressure in the joint when the pipes are bent into an arch. Once joined, simply use permanent marker every two feet starting at the center.
Before wrapping the lights, you should decide how you want to run the power lines up to the channels in the middle of the arch. Some I've seen simply run the extension cord on the back side of the pipe after all the lights are on and zip tie to the pipe. Others just dangle the cords straight to the ground. Since the controller is located between two arches and all the lines need to come together there, I chose to keep the lines all neat and concealed so I ran the lines through the pipe. To do this, I started at the far end of the pipe and wrapped the lights so the end was towards the end where the cords were going. I then drilled a 1/4" hole in the pipe and fed the cord through the pipe. The cord was SPT-1 that was spliced into the lead on the lights after cutting off the plug. The plug was then spliced back on the other end of the cord once it exited the end of the pipe. I continued that until I reached the center where the pipes join. I then changed to run the wire on the outside of the pipe since it was easier to do that and turned out to be a good thing (explained later). After the first set past the joint, the cord was simply taped to the pipe with electrical tape and then the next set of lights wrapped right over top of the cord.
The best part of having the joint in the middle and the cords running through the center is the two pipes can be separated and "folded" in half for storage. I could add butt splices in the cords and they could be completely separated but I don't think it is necessary. It's not that hard to handle when they are folded and they store easily on hangers in the garage. When they are getting setup, I used 4' rebar cut down to 2 1/2 feet. About half of that goes in the ground and the other half will go into the pipe. The one difficult part of this is on the end that has 4 lines coming out (remember half the cords to the lights run inside the pipe). It is a bit tight with the rebar also going in the pipe, but it does fit as long as you can keep the lines laying fairly flat and not tangled up. Smaller diameter rebar could also be used but I've managed to get it all together just fine so far. If you calculate out a perfect circle diameter given a pipe of 17ft you would get 10.8 ft. That would give a half circle look, but I didn't like that. So mine are spaced around 12ft to give more of an angled look.
Here is a closeup on the first set of lights:
Here is a closeup of the joint in an arch (notice the cotter pin):