Well, I myself am pretty "into" plastic models as well as Hotwheels (I have 2000+ in the package).
As far as a body kit, there could be many approaches. You could create the kit out of styrene. You could use body filler and sculpt it the way you want. You could create molds and cast your own parts. There are pretty much limitless ways to attack this. I guess I want to know what materials you are looking to use.
Here is a link to a post on this forum about model cars.
http://www.photoshopchop.com/forum/s...ad.php?t=12389