Hi Lloyd,
for starters, have a look at www.hirstarts.com/casting/plastic.html
It'll tell and show you about the process and also on some brands of resin.
Some other info can f.e. be found on www.starshipmodeler.com/projects/jw_resin.htm
One of the reasonably popular brands seems to be Smooth-On, whose products and dealers can be found on www.smooth-on.com
I have no experience in this whatsoever, yet as I am contemplating
doing some casting myself I did some searching the other day. :-)
Cheers,
Jan Martin Wagenaar