Work started on the original body design while Clive was still completing his National Service in the RAF. He made three wooden mock-ups (roughly a foot long each) during his leave and spare time. Once he had completed his National Service and a design had been chosen it was lofted-up and made into a life size buck made from aluminium, wood and plaster. The nose and rear of the car then underwent a fair amount of modification before the brothers were satisfied with the design. A mould was made from this buck. Unfortunately the original buck was destroyed while removing the new moulds.

The first bodies to be produced were "complete" shells and did not have any openings cut into them for doors, boot, bonnet, headlights or wheel arches (as seen in this advert from Super Accessories). This helped reduce costs and production time so that they could get bodies cheaply and quickly into the market. The other reason for not having openings was that the bodies were intended to be sold to "Specials" builders for constructing racing cars. To keep aerodynamic drag to a minimum only the necessary holes need be cut. Headlights were only mandatory in "Sports Car" categories but were not required for other forms of racing. Since the car was quite low, doors were sometimes not used either. Every little helped in racing.

The bodies were made to order with delivery being quoted as between 4 and 6 weeks. A range of colours were offered so the new shell would not require painting. Soon options were being made available including a removable hard top which had gull wing doors which were very much "in vogue" at the time. Doors, bonnets and boots became available. Dashboards and bulkheads could be specified, and inset headlights called the "Le Mans" option were popular (seen in the picture at the top of the page). These more luxurious bodies were sold as "Vitesse" or "De Lux" shells. Buckler cars, who also made "Specials" and chassis bought a number of shells to make into cars. The picture at the top of the page is of one such car - having a Buckler DD2 chassis.

It was not long before the Roadster shell was offered with Convair's own boxed in Ford chassis, and soon afterwards Convair developed their own spaceframes chassis designed to fit a range of popular mechanical items (e.g. Morris Minor, BMC A-sereis, Ford 1172cc sidevalve and Coventry Climax engines, with BMC rear axles and gearboxes). Due to the shape of the shell Convair designed their own radiator and header tanks, and had various windscreen options made for them (split screen, single piece curved screens, or wraparound perspex screens). Hoods, sidescreens and tonneaus were also available making for a very useable car.

Since the Roadster body was designed as a racing car shell it was made as light as possible. This lead to some weak areas, such as the front wheel arches and the bonnet/boot lids. These areas could be strengthened during manufacture if required (usually by glassing in sections of garden hose pipe). The shells were very thin and could be lifted by one man (just!). It is no surprise then that very few of the 120-150ish made still survive today.