The tools you need are;
A dremel with sanding drum or some fine sand paper (220 or finer)
Some putty

Squadron or tamiya is highly recomended, stay away from testors.
and some imagination.
Attaching the putty to lexan or any other plastic is pretty easy, it sticks to it well. The one piece of advice I can offer is to go light on the putty, the more putty you add the heavier it gets. If you wanna make body kits use lexan and cut it to size and shape you need. You can buy lexan sheets in different thicknesses. I tried twice to make a body out of putty and lexan but they both came out like crap because I was impatient. TAKE YOUR TIME with it, mold the putty right the first time and you'll save yourself alotta grief later trying to sand it down.
I hope this helped somewhat.