I just found a nice webpage for you.
Here are some plans for a very basic vac-u-form setup, great for giving you a quick idea of how this process works. This particular article is VERY basic, but if you click on the related articles to the right, you will find more in-depth vac-u-form setups, all with instructions. Also here are some nice articles on mold making and casting.
(As an added bonus, the looks your wife gives you as you play with saran wrap, an empty plastic jar, tape and popsicle sticks as you sit at the couch watching TV with her are PRICELESS.)
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http://www.instructables.com/id/How-to-Make-Your-Own-Prototypes-%3a-How-to-make-your/#comments