Is this chassis too small???

[Balidey]

You shouldn't be using this process to make several. Its 'rapid prototype' technology. The clue is in the title . If you are going to make several then you should really make a mould from 1 and then cast several.
I am sure Tamiya did a Caterham kit a few years ago, but a 'true' model of a Haynes Roadster would be a cool thing to have.