Vacuum forming plastics isn't that hard if you have the right equipment. The company that I work for builds all sorts of vac-tools for the auto industry, & I design the tooling. As far as doing it at home, it really depends on how much time & money you want to invest, & how experienced you are with building things. A simple vac-table can be made out of 1/4" plywood, 2 x 2's & peg board, & a fitting to fit your vacuum cleaner (preferably a large vac). You will need a clamp frame to hold your plastic while you heat it, which can be done with a heat gun, or your oven (which give more consistent results, but might stink up your house a little)
Since you already have the pattern, you have the hard part done. Just make sure that you don't have any sharp corners (less that 1/8" radius) because the plastic might wrinkle instead of conforming to the pattern. If you want really constant results, & have a drill press that you can set the depth of the stroke, you can drill some 1/4" holes from the back to within a 1/4" of the surface & connect them from the front with really small drills like .040"
Hope this helps, if you have anymore questions, let me know.