If you have a really cool object that would be a starting point for some great clay art, you need to make a mold of that item.
Especially if you want to keep that mold to reuse multiple times, a silicone mold is the best way to go. However you may not want to have a big container of it sitting around.
The perfect, portable answer are these 1 oz 2-Part of compound.
This two-part Rio Cold Mold™ silicone molding compound lets you mix up a small amount of compound quickly and easily with no measuring or guesswork. The compound is compact and portable; you can carry it with you wherever you go, and capture a unique pattern or texture in minutes. It's ideal for molding delicate originals, master models and for use with metal clay. Rio Cold Mold™ compound delivers 0% shrinkage without heat. To use, combine equal amounts of each part, and mix thoroughly; no release agent is needed.