I fabbed up an exhaust a couple weekends ago. Since this a two-stroke motor, I ran through some calcs to determine the size and shape of the various cones for the expansion chamber. I built everything out of 3" exhaust tubing I got from NAPA. That means cutting down and shaping the cones by using good old brute force. I wanted to do something different, so I ran the exhaust through the middle of the frame. Making the divergent cone was trickiest, as it needed to bend 90-degrees, while still coning down to its final diameter. Lots of pie cuts and welding. Still needs some finishing work, but the entire thing will get wrapped anyways.
The last three shots show a wood seat and rear cowl I built, using layers of poplar. Lots of shaping and sanding, finished with five coats of gloss urethane. Still need to make a rear mount, license plate bracket, and figure out a taillight.