R.Q. Riley created a whole line of cars in the early 70's which were sold in the form of plans and instructions that the builder would use to fabricate the car from scratch. They were periodically featured in the
magazine Popular Mechanics and were renowned for their ingenious construction. All of them were made from off the shelf parts (mostly VW) and urethane foam / fiberglass sandwich bodies. One of the most popular and
recognisable of these cars was the Tri-magnum. This car
was, in fact, so popular that other companies got liscense to offer the car as a complete kit. Plans are still available on R.Q. Riley's website.

The Tri-Magnum was a swoopy, futuristic 3-wheeler based on a motorcycle drivetrain ( of the builder's choice ) and a VW front suspension. Kit versions came with the complete body and a tubular steel frame. If built from plans the frame had to be fabricated by the owner.
Braking was handled by VW drum ( front ) and disc brakes from the motorcycle donor at the rear. Steering was accomplished using the VW bug steering box. Since most motorcyles don't have a reverse gear and electric motor was used to facilitate backing up. The car featured a wild flip-up canopy and pop-up headlights.

For more info on this car see the above hyperlink.