The trick for making a Twinkie mold from is quite simple, and easy to get the hang of. And if you're making Twinkies for the legions, I recommend making the half-sized molds that I used. In fact, just do it that way.
Cut twenty four 9" sheets of aluminum foil
Fold each piece of aluminum foil in half twice.
Wrap the folded foil around a small spice bottle to create a mold.
Leave the top of the mold open for pouring in the batter.
Arrange on a cookie sheet or in a shallow pan. Spray molds with non-stick cooking spray.
Preheat the oven to 325F (160C)