I've (more or less) followed Saturn's MX5 design. He's kept it as close as possible to 'book spec', so there are very few changes.
If you get hold of his build guide it details all the changes he's made. It should be available for download on Monday, or over the weekend if you email him. Look for Spud's thread in the chassis section.
I hadn't done anything like this before I started my build and only had a couple of hours welding experience. You soon pick up the skills you need. Belive me, if I can knock up a chassis anyone can!
What I don't mention in my thread is all the mistakes, dodgy welds, and bits I've had to re do
It's all part of the learning experience though!
If I could go back in time 6 months I'd do a welding course before I started, as it would have saved me a whole lot of trouble!