Molds

Molds are a simple way to make multiples of the same (or very similar) items. Highly detailed molds enable you to replicate a favorite shape with reliable results. More basic molds allow you to build your own design by stacking or otherwise combining shapes.

As polymer clay grows in popularity, so too does the variety of polymer clay tools on the market. The polymer clay section of your local craft store is probably stocked with a selection of molds made especially for use with clay. (Flexible molds are popular because of their ease of use.) You can also look for molds in the resin, soap-, candy-, and candle-making aisles of craft and hobby stores. For even more ready-made molds, type "polymer clay mold" into your favorite search engine and browse to your heart's content.

If you can't find a ready-made mold to suit your desires, or if you wish to save your money for something else, you can always make your own mold. It is possible to carve a shape to use as a mold, but an easier way is to find the shape you want (or sculpt and cure it in polymer clay) and make a mold from that.

Molds can be made from plaster, silicone, Sculpey's Super Elasticlay, and other materials. Polymer clay-particularly scraps left over from other projects-can also be used to make molds. Regular clay will yield a rigid mold. For a more flexible polymer clay mold, try Sculpey Super Flex "Bake & Bend", which can be used straight from the package or mixed (commonly in a 1:1 ratio) with another durable clay, such as Kato or Premo.

Make a mold from polymer clay.

Whether you're using flexible or regular clay, it should be well conditioned. Knead it thoroughly. Form the clay into a ball or thick slab. You need enough clay to accommodate the item you're taking a mold from.
Take the item you wish to make a mold of and treat it with a release agent. Popular choices for release agents are water, baby powder, cornstarch, and decorative powders (such as Pearl-ex mica powders). Use a spritz bottle to apply water. Apply powders with a brush or a ponce bag. Remove excess. (Too much powder can obscure the finer details you're trying to capture in your mold.)
Firmly, and with even pressure, press the item into the ball or slab of clay. Try not to wiggle it, as this can lead to double impressions.
Carefully pull the item away from the clay, trying not to distort the impression.
Examine the impression. If you see double impressions or other flaws, you can simply wad the clay back up and try again. It may take some practice to perfect your technique, but fortunately, you can "re-do" it as many times as you like.
Once you're happy with your impression, you can trim away any excess clay to save for another time. Bake the clay according to the manufacturer's instructions.

The following are a few other things to consider when making molds from polymer clay:

If you're taking a mold of a metal object, you may not have to remove the item before curing the mold. Because metal can withstand the temperatures required to cure the clay, metal objects can be left in place and removed after curing. The benefit of doing this is that there is less chance for distortion of the mold. However, you'll want to be sure to use plenty of your release agent, and remember that the metal will be very, very hot for a while after removal from the oven.
If you're making a mold of a double-sided object (such as a coin or checker game piece), you can do so by making two molds-one for each side of the object. You can do these at the same time or separately. When making two-part molds, it's a good idea to leave a mark on the edge of each part of the mold to indicate where the two should line up.
Even if the object you're making a mold of doesn't have two decorative sides (say, for instance, a button), you can still make two molds of the same object and use them together to make a bead or other double-sided item.

As you'll soon discover, the world around us is full of items to use in mold-making. Just remember that nothing that touches the clay should go into your mouth or your food. Also, if you want to take a mold of something that may react with the clay (varnished or painted wood, some plastics, etc.), you'll want to consider how upset you'd be if something went wrong and the item were damaged. If the object is simply too valuable to you, maybe you'd better hold off. However, most objects can be safely used-particularly if you take care to clean them with rubbing alcohol immediately afterward contact with the clay.

The following list contains a few suggestions to get you started in your quest:

Beads (especially beautifully carved or textured ones)
Other jewelry components (lockets, pendants, etc.)
Buttons (again, the more ornate, the better)
Small toys and trinkets (such as Cracker Jacks prizes and Happy Meal toys)
Seashells (or coral)
Leaves (for very thin molds)
Sticks or twigs
Food (hard candies, pieces of cereal, nuts, etc.)
Dog bones (or other treats)
Keys
Seedpods
Small bottles or interesting bottle caps
Dolls (faces, hands, feet, etc.)
Your own sculpted items (faces, tiny animals, flowers, abstract shapes)

How to use a mold:

Prepare the mold by treating it with a release agent. Products that work for making a mold also work for casting a shape from it. Water and powders are popular choices. Be generous with your release agent, but remember that using too much will clog the mold and prevent the finest details from transferring completely.
Form your well-conditioned clay into a ball or a sheet. (For deeper molds, a ball works best. For shallow molds, a sheet will suffice. Experiment to see what yields the best results with your particular mold.)
Place the ball of clay into the center of the mold. Press the clay firmly and evenly until the mold is filled. Depending on how much clay you use, some clay may overflow around the sides of the mold. (This overflow may or may not be a problem. If excessive overflow gives you trouble with removing the casting, try again with smaller and smaller amounts of clay until you learn exactly how much to use.) Avoid rocking the clay back and forth, as this can cause the clay to move in the mold. The result is often distortion or double-impression of part of the pattern.
Remove the clay from the mold. You may be able to simply lift the clay out. However, if you find that you have difficulty removing the clay without distorting it, try these methods:
1. Attach a plug of scrap clay to the back of the clay in the mold. Use this as a handle to pull the clay out.
2. Allow the clay to cool before trying to remove it. You can even put it into the fridge or freezer to make it firmer.
3. Start with refrigerator-chilled clay. This is especially helpful if you are starting with soft clay.
If there is excess clay (overflow), carefully trim it away with a craft knife. Now is also the time to do any tweaking to the shape, before you cure it (according to manufacturer's guidelines, as always).
It's good to cultivate a habit of cleaning your molds with isopropyl alcohol after each use. This will make them last longer, and it will also make the next use easier-- no sticky residue to contend with.