Places to Buy Products
Tap Plastics
   Great S.F. Bay area resource, especially for beginners. Where we go when it's the day before the con and we've run out of materials... this happens way more than it should.

Silpak
   Located in the Los Angeles area. We really like their polyurethane quick cast resin.

Smooth-On
   The website leaves something to be desired but they have great products. Their stuff tends to require some know-how but we really like their mold rubbers.
How-To Resources
The Prop Builder's Molding & Casting Handbook
   All encompassing guide to making props with varying techniques from very simple, like hot glue casting and paper mache, to more advanced techniques, like fiber-glassing and vacuum forming

Do It Yourself Vacuum Forming
   Put out by Tap Plastics. Great guide to building a vacuum form setup at home using stuff you can find pretty easily and for fairly cheap

YouTube
   There are a lot of how-to videos posted on YouTube. Tap Plastics has tutorials posted there too.
Materials We Talked About
Polystyrene / ABS plastics - used for vacuum forming
Polyurethane Resin - a resin you mix and pour into molds
RTV Silicone Rubber- a mix and pour rubber that you use to make molds
Polyester Resin - a clear resin
X-30 expanding foam - a mix and pour foam that expands
Fiberglass - a paper mache like material using glass cloth and epoxy