I agree with O2Pilot you need a pretty good shop for this. Something a heavy guage aluminum tubing would be a starting point then you need a tubing bending machine like a plumber or muffler shop uses. after that a big oven for heat treating. I am not sure you would use the simple heat and quench process for aluminum but a heat and cool in a certain timed fashion.
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“One morning you wake up, the girl is gone, the bikes are gone, all that's left behind is a pair of old tires and a tube of tubular glue, all squeezed out"
Sugar "Kane" Kowalczyk