For my exhaust header, I shaped a centerline from an old brake line and had a local company that bends railings for boats make it from ¾ " tubing. They suggested using stainless steel tubing, but I wanted mild steel for an authentic rusty appearance.
I used an old elliptical 30's Chevy brake light for a head light and had a new lens cut from fluted clear glass at a local stained glass shop. I wired Mini Maglite 2-Cell AA Xenon replacement bulbs ($3.25 a pair) into the light housing reflectors because of their bright intensity and size.
Because I am versed in composite construction (www.AeroChia-LT1.com), I made many parts from scrap carbon fiber cloth we had laying around our shop. Less expensive Fiberglas cloth would have worked well too. I made a fender, seat pan (covered in leather from an old brief case), chain guard, brake lights, switch /AA battery box, a fake oil pan and a vintage license plate.