Kawboy's tail-section work inspired me to post what I am slowly working on. I didn't want to hijack his thread, but I did post a bit about it. Here is what I am working on.
I had a Motorvation Spyder sidecar on my '83 Voyager as seen in my profile pic. That was just a sweet rig and the hack was attached for most of the bike's 200k+ mile life. That sidecar in stock form looked good with that bike, but now I can't afford to buy a new Spyder, but I have lots of time, skills and equipment to build one. Starting from scratch allows me to match the profile outline to the bike's. Below are a pic of my bike in profile and the preliminary sketch of the car's profile outline. The goal is to make the nose match the bike's fairing nose and the tail to match the bike's trunk tail. The original Spyder's tail section had a flip-top for access to all that storage space behind the seat. Mine will have almost the same space with the same flip-top. Not sure if I will try to fit a duplicate headlight in the nose of the sidecar as on the bike, because that would make construction in that area quite complicated to seal up.
The basic technique for this build will be to use 3/4" diameter aluminum tubing welded up into the basic outlines, then a skin of aluminum laid over them. The skin would be tacked to the tubing, then gently hammered around the tube to butt up against the edge of the adjacent panel. A bead would close that gap and then will be ground smooth for a seamless appearance. The 3/4" tubing will determine the radius of all of the panel intersections. It should be a super-strong, but lightweight, monocoque structure. Some tubing structure will be applied inside for attachment of the suspension and for rigidity.
Motorvation uses fiberglass to form the body shell, with steel plates sandwiched inside multiple layers of glass. To these plates they attach the suspension and mounting framework. Even as heavy as this sounds, their whole rig weighs just 265lbs! Pretty lightweight as most sidecars go. The Spyder really is a very nice sidecar!
I plan to add a "model-T" styled removable top and a "Duvall" style windshield. I have an old Airheart disc brake from my go-karting days that will fit and work quite well on this 'car, as it did on my old 'car. I already have the heater core and fan to add heat and a 12 volt screw-jack for leveling. Not sure if I will add a gas tank to this 'car or not.
I would just like to say that almost anything can be done with a little imagination and a little bit of ingenuity. Even paper-mache(sp?) can be used as a starting point to fabricate sections. Fiberglass is quite easy to work if you can stand the odors and have lots of patience. Add some balsa wood, or even some cardboard, as a base material and almost anything can be made. Don't be shy! Kawboy isn't!