I've done this a couple times for one bike--the first try didn't work so hot, so I cut it up and made another that was better overall.

http://www.norcom2000.com/users/dcim...n/general.html

I made mine out of 3/8" and 5/16" OD tubing I bought from a local metals supplier. I would think that steel rod would end up rather heavy, as the stiffness depends a lot on the outer diameter. Racks made out of aluminum usually use solid rod, but racks made out of steel tend to use tubing.

I probably used ~$50-$60 worth of tubing for the second attempt. This bike being rather unusual, nobody makes a rack that's really tailored to fit it (-nothing off the rack! har har-) and the manufacturer makes an adapter kit for normal racks that shifts them back 3-4 inches, but for a taller rider the seat will still overhang the rack a lot, preventing attaching a normal trunk bag.

I attached mine with 4-bolt clamps that I made, because the puny screws that US bike companies use to hold racks on are simply crap. The disk brake made attaching it at the rear dropout a problem and the seatstay tubes were un-tapered anyway, so making clamps just made sense. I also welded a pair of hooks bent from 1/16" x 1/2" steel on both sides, to hang grocery baskets from.

I use an oxy-acetylene torch which I like for working with steel, because you don't have to weld everything--you can heat steel red-hot, bend it into a shape you need, and after it air-cools again it is still as stiff and strong as before. If you bend the same metal cold, it loses a lot of its strength and stiffness.
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Aluminum can be welded and brazed with the same kind of torch, but it's more difficult to work with than steel and the heat-affected zone of aluminum tends to soften a lot (unless it is heat-treaded again, which you can't really do at home). I use steel for welding projects unless for some reason I must use aluminum.

The first attempt I carefully planned out in a CAD program, cut all the tubing and welded it together and it ended up a mess overall. It sat too high and not level. The second one I eyeballed most of the way, cutting everything slightly over-length so I could trim it to fit and only using a tape measure to make sure parts were generally cut to the same lengths, and it ended up a lot better overall.

The kickstand didn't turn out ideal, but it still works way better than anything else I could find. With the grocery baskets on, I can put three 2-liter bottles of soda in one basket with the other empty, and (on level ground) the bike won't fall over. I'd have liked to make it spring-loaded like a "real" kickstand is, but that would require a solid attachment point on the frame a couple inches long, rear of the back axle. I wasn't quite courageous enough to try that this time around.
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