Silicone Putty is a flexible mold making material, that is food safe and can be used with plastic, urethane, epoxy, polyester, concrete, and more.
To use the silicone putty, just knead equal parts of A + B together, and immediately apply it to the surface of what you want to duplicate. It could be an action figure, a pebble, an artifact, or anything at all. Make sure the putty has completely surrounded the object, and let it sit for 10-20 minutes. Come back, and lift it off. You now have a tough, flexible and reusable mold.
Very fun stuff. I would highly recommend using silicone putty as a mold for our casting urethane. By using a combination of both, you could potentially make a mold and finished piece in less than 45 minutes.
Silicone Putty is great for small items that have a flat bottom (as opposed to objects that need a 2 part mold) Use a mold release to extend the life of your mold.