Hi KMD,
Some years ago I needed to repair my S6 stand and found that a very close copy of the correct section tube could be made by re-rolling some 3/4" dia x 16g tube. I used a sheet metal workers swager (some refer to them as 'jenny's'). I used one half round wheel/former, and one flat wheel and then gradually produced the flat by running the tube through about 10 times. If you get too ambitious, the tube collapses into a heart shape. If this happens, it may be neccessary to make a bar to go inside so that it supports the centre of the flat while you are rolling it. With care, you should be able to produce separate pieces long enough to make the legs and cross brace without too much of a twist or bend in them. When you have the correct section, fashion up some wooden bungs for the ends, then pack the tubes with DRY sand (builders sand will do) - you will then be able to bend the tube to the required curve for the legs without it collapsing. This can easily be done freehand in the vice if you have facilities to heat the tube to just a dull red before trying to bend it.
Hope this is of some help,
Regards,
Eddie.