Hmm, a cable reel, novel thought if you have one. What I used was a 5/8" solid aluminum rod obtained from a local metal and welding supply in Wasilla. I think I paid somewhere around $13.00 for it back a few years ago. Unfortunately, I do not have aluminum welding equipment and the longest length I could get locally would only do a 4' hoop, but that is large enough for me. If you have the aluminum welding capabilities, you could add on, but keep in mind that the process will change the bending characteristics of the rod at that joint.
The next step was to bend the ends with a conduit bender so that they would fit into the end piece that connects the pole with the hoop. This is more or less 90 degrees and can be adjusted later. If you don't have a conduit bender, you can always use a vise and a piece of scrap pipe to get the bend, but you will probably need an extra pair of hands and a lot of space around the vise.
As to the piece that connects the pole to the hoop, I can't remember the proper name for the extruded aluminum thingamabob right now, but I am sure you know what I mean. I would opt for the heaviest duty I could find in 5/8", and I believe I got mine from Donalson's. I also opted for the 1 1/4" inside diameter poles. I don't know if it makes that much difference or not, but most of these poles I have seen are blue, but I paint at least the first section from the hoop back a neutral gray, beige, or dull aluminum.
I then took a 5/8" piece of plywood, cut it into a 4' circle, glued rails on each side at strategic locations to keep the rod from slipping off during bending, secured my starting point and then slowly hand bent the rod around the plywood circle. It was not that hard and the hoop has held up well and looks good. However I did have to take the completed hoop and lay it on a flat floor to make a few adjustments so that it would lay flat. This would all be an easy process with a large slip roll, but not having one, I had to improvise, but came out with a very strong hoop that is not too heavy. The poles and the end piece that connects it all together I purchased from B&J and Donalson's in Anchorage.
Oh, a few other tips, I always carry an extra net bag with me just in case and seeing as I am very inept at tying knots and can barely tie my shoes, I make small net repairs with any sort of knot I can make and put a spot of super glue on it and have never had one fail or slip. I also coat the hoop rod and pole ends with anti-seize in the event I ever have to take them apart so that they will not become bound up with silt and sand. Probably everyone knows, or soon learns, that you should always break down your poles after use and clean them, but few remember to do anything about the connections between the hoop and the end piece. Believe me, they can get stuck to the point that they are impossible to remove, but the anti-seize will keep the silt and sand out -- hopefully. One further tip is to take a section of 5/8" ID garden hose, preferably a neutral or green color and split it lengthwise, then use enough to cover the area of your net and hoop that rest on the stream bottom to keep from abrading the net around the hoop. This can be secured with high quality electrical tape at strategic points. Some folks use zip ties, but they catch the net and hang it up and are a pain.
Good luck with your project and please let us know how it turns out. Feel free to contact me with a PM if I can be of further assistance.
Please everyone, lets keep the areas we recreate in as clean or cleaner than we found them. Pack it in, pack it out and maybe a little more that the pigs left behind as well.