Well cage making is pretty easy if you have strong hands, not so easy if you don't. You will want a good pair of gloves and wear safety glasses. The reason for the gloves is obvious, but the wire is stiff and curved and springy and somewhat hard to manage and with those sharpe legs exposed once the wire is cut is a real danger to the eyes.
I use a pair of aviation pliers to cut the wire, they allow a close smoother cut.
This is what I normally buy:
You have to calculate how big in diameter your want your cage to be. I usually count out twenty four sections (a section here would be 2 inches ), then I use a pair of aviation sheet metal cutting pliers and cut down the full height of the fencing (four feet). Looking at the photo of the fencing that would be 13 cuts. You want to leave "legs" when you cut the wire so you can use your hands or pliers of some sort to connect the circles you form. You just form a circle with the cut section, then bend the legs around the opposite end of the circle formed. It takes a little practice getting all the legs aligned correctly. Now you have a four foot tall cylinder.
Then you cut as described below.
Now you have to decide how tall you want the cage to be. I started off with them way too tall, four and five sections high, but I also made them as low as one section and two sections high (a section being 4 inches in hight). For my purposes I have come to prefer three sections plus the "legs". These "legs" push easily down into my soil, but if you have clay or hard soil you might elect to used a stake to hold the cage in place.
The "legs" don't provide much stability and I did have to stake a few at first to keep the critters from pushing them over, but then they learned to just dig around them and that is unsightly but seem to do no harm to the plants. The deer still occasionally have a hissy fit when their horns or feet get caught up in the cages. Sometimes I never find a displaced cage. Usually I just have to straighten it back up and replace it. I don't recall any of the plants in that case being harmed. The Armadillos have to be removed because of the tremendous damage they do, but the cages do help protect the plants until the pesky thing can be trapped and removed. That involves a different type of cage.