Cooking sprays are not just for the kitchen. Normally they are designed to help keep foods from sticking to cookware, but they are also useful in preventing other things from sticking together. It is a great product because it is nontoxic and won't harm the resin or the mold.
Talcum powder can be used as a mold release agent with flexible silicone-type molds that are not incredibly detailed. It wouldn't work well with solid, inflexible shapes as it won't coat the mold enough to prevent sticking within detailed areas
Petroleum jelly is a suitable mold release agent for simple molds without fine details. If it used on a very detailed mold lost of details on the finish resin object may be lost.
Vegetable and Mineral Oil
Mineral oil can be applied by rubbing the oil into the mold with a paper towel. If applied too thickly, either type of oil may pool within some of the mold details. Excess oil can be absorbed with a paper towel.