I did this at TechShop Menlo Park. http://www.techshop.com
here are many different types of molds but when dealing with something with a large amount of undercuts such as a chicken foot a strechy, rubbery silicone mold works best.
Step 1: Make a Container
Silicone is expensive so in lack of a smallest possible container to house the object I created one out of packed cardbord and blue tape. This container is easily dis and re- assebled so it will fit several different objets I'm planing to make molds of.
Step 2: Use Dry Objects
I dried my chicken parts in the oven on very low with the oven door cracked over night.
Step 3: Mix Silicone
Mix one part to one part trying to introduce the least amount of bubbles possible. When picking mixing supplies read directions for the materials silicone reacts to. You cannot get it in touch with latex gloves (wear nitrile gloves), or plastic wrap or silicone won't cure properly.
Step 4: Pour Silicone to Make a Mold
Pour half of your silicone mixture into the container. When pouring, choke the silicone by pouring in a thin stream high away from the surface being poured on to get rid of any bubbles. After about 5 minutes it will become tacky. At this point invest your object only half way into the silicone. Wait for it to cure. If you use quick setting silicone you will only wait about 20 minutes. There are different types of silicone so read directions carefully. I like platinum quick setting silicone best.
Spray mold release all over before pouring the second part of the mold.
Now you wait for the silicone to fully cure before taking the mold apart and taking your object out and reassembling your mold with a cavity you can pour many substances into to make replicas. I am using it to pour hot wax into to make chicken foot and head replicas to lost-wax cast them in aluminum. :)