They were indeed the first. Mr. Curtiss was quite wealthy and built the first Aerocar for his own personal use with no intentions of ever offering them to the public. Those who did buy them paid about 10 times what an average American car cost at the same time. A new Chevy was about$ 800.00 while and aArocar was $ 8,000.00.These did not have a steel frame. They were built from wooden oak lumber. The side uprights were tensioned together with steel aircraft cables tightened with eyebolts. The fabric for the exterior was called Fabricoid and was then painted as an attempt at waterproofing. Interior furniture was commonly made from wicker to keep the weight as low as possible. Obviously a lot of those details were based on the experience he had with building aircraft in that pioneering era.