Manufacturing process, including sketches.
Before rolling, the edges need to be folded and filled to create a rounded edge to create a large enough radius to prevent the skin from wearing too hard. This was done by laying a wire of 3 mm diameter in the folds along the sheet (see also figure 1).
To ensure a smooth joint, a kind of step should be made by folding a corner at one end of the sheet, see side view in figure 1 and figure 2. It depends on the equipment you have to your disposal, I made it before rolling the cilinder as I did not have the means to do it afterwards. Make sure to make the step in the same direction as to where the other edges were folded.
After folding, cut the shaded corners seen in figure 3a.
Now roll the folded sheet, make sure the folded edges are on the inside of the cilinder. When the ends meet, it should be possible to connect both ends by simply sliding them over each other and then riveting them together. See also figures 4a and b. Make sure that the size of the cilinder is correct by fitting a skin. Also avoid leaving a gap between the two ends, as the skin could pull both ends further together.
Use clamps to hold both ends together while drilling and rivetting, if possible extra around the hole you are drilling.
After welding, mark out 8 points at equal distances around the circumference of the ring, drill holes and cut M12 thread. Insert an M12 bolt in each hole and tighten it. In figure 5a is schematically shown what you will end up with.
Now mark out the position on the bolts for the holes through which the tension rods are to be inserted. Also mark the distance to cut off the head of the bolt. The dimensions are given in figure 5b. At the dotted line marked with "D" the bolt should be cut off. The trailing threaded end at the inside of the ring should also be cut off.
The result of cutting and drilling is given in figure 5c. In this figure it is also shown how to make the slots where the tensioning rods are inserted to prevent twisting. Only one rim needs to have these slots, by the way.
The rims are now finished. I chose not to secure the insertion points (yet) to see how that works. You may want to fasten them using e.g. "Loc-Tite TM" or by welding.
After ensuring the rods fit, round the sharp edges of the flat end to prevent injury.
Use regular M6 nuts to fasten the rods.