Here is my cardboard tube again and this time I'll be making some rings that go around it, four of them to be exact. Like I said before, the plan is to stack these so they go from floor to ceiling. Now the height of the ceiling is about 10 feet, that means two full length tubes and one that will be cut to size, about two feet long.

The rings will be made out of 1/16" thick mild steel sheet, then bent and welded together. These rings will be placed at each tube joint to help hold everything together. The bottom ring will be six inches tall and will be attached to the concrete floor. This way it will make sure the tube won't move and stays stable. The top ring will attach to the ceiling and will be two inches tall. There will be two middle rings that will be four inches tall and they will join the top and bottom tubes together. And last, these rings will also have large bolts welded in them to help simulate the construction, but really won't be functional.
 

Here is the 1/16" mild steel sheet that I'll be using. The two square pieces at the top are going to be base-plates for the top and bottom rings. The base plates will be round when finished. The rest of the material, is for the rings.
 

Here I'm cutting out both bases at the same time using my jigsaw. To make sure they stay together I'm using some clamps that I move when needed. Once they were cut out, I used my belt sander to remove all the sharp edges.
 

The next part that I'm doing is putting holes in all the rings for the bolts that I mentioned earlier. What I need to do is put eight holes in each ring that will be equally spaced apart. However, the four inch wide rings will have 16 holes in them (two rows of eight).
 

I made an aluminum pin that is two to three thousandths smaller than my milling cutter. Then I used that same milling cutter to produce a hole in the piece of wood that you see below (the pin is a slip fit now). I also bolted that piece of wood to the mill table so it wouldn't move with some flat head screws. With this setup, I can machine one hole in my work piece, loosen my clamps, move my work piece over and have that hole locate on my aluminum pin (which is a calculated distance) so they're all equally spaced when I'm done.
 

Here I'm trimming my material two inches oversize. The reason I'm leaving it oversize is because when I form these into round pieces on a tri-roller, the material doesn't form well when it exits and leaves a small flat area. Once I'm finished with the tri-roller, I can trim off this excess material leaving a nice round work piece.
 

Here is what a tri-roller looks like. It has three rollers, (hence the name tri) and is adjustable to form different size radii and thickness' of material, depending on your needs. Now this isn't the actual tri-roller that I used as I forgot to take a picture of it while using it at my old work. And some tri-rollers are motorized, because as the material thickness increases, so does the friction making a hand crank useless.
 

Here is how a tri-roller works, you feed your material into one side and then crank the handle. As you crank the handle, it drives two of the three rollers feeding your work piece through them. The third roller is adjustable fore and aft, allowing you to adjust your radius size. It's a simple design that works very well.