pic: Wet layup mold system

You can use just about any material (except styrofoam which will melt even through plastic) for a mold then cover with the heat shrink plastic you can buy for window insulation. Shrink it with a heat gun and its ready to use. If you want to make multiples of the same item it works better to make a positive mold (buck), then make a negative mold, wax the snot out of the negative mold (use release wax if you can find it) then make the parts. I never used a bagging system, only wet lay up, but if you coat the interior of the well waxed mold (I usually did 10-15 coats of wax on a new mold) with epoxy, then the layers of cloth, making sure all the cloth is coated and then put your buck on top (with the plastic cover if necessary) then add some weight and set overnight it will give results as good as many bagged systems.