The building process starts with the donor vehicle. The body shell and seats (depending on model) are disposed; everything else goes to the Corsa Spyder which is designed to utilise everything from the Triumph Spitfire. This saves a lot of time searching for donor parts.
The Type 48 Corsa Spyder is a car that you build, not just assemble from parts that are simply bolted together. With a lot of flexibility inherent in the design, no two cars are the same. Everybody seems to have their own ideas about how they want it to be.