The fimo began as the older brother of the clay to those skilled than eager to create their own pieces without sacrificing durability, color and quality. Today we can find true works of art and many artists who have been innovative with something that at first seemed like a game.

Fimo, Sculpey and Cernit are trademarks mouldable mass or dough that are baked for hardening.
Fimo The term is used generically to refer to all types of modeling pastes (similar to clay), which harden when heated.

Composition (source: wikipedia):

The base composition of these masses to model is PVC, a plastic polymer made up of several molecules (monomers) of vinyl chloride. The polymerization process of vinyl chloride is highly toxic and takes place in factories in sealed reactors.
The mass of PVC found in the market is not toxic under normal conditions, toxic fumes are formed only if there is combustion or burning of the dough in the oven, for this reason should not exceed either the temperature or the time specified in the product label.

Use (source: wikipedia):

With fimo we can do all sorts of figures. For its range of color and consistency is especially suitable for the creation of small decorative objects, including jewelry items like earrings, bracelets, rings, necklaces, etc..
You must knead with hands for a short period so that the pasta it more elastic when it absorb heat. It is very easy to model and presents different colors that can mix well together. To model this paste and achieve different finishes and textures can use the tools used to shape clay or plasticine.
After giving the dough will cook as desired in a home oven at about 120 ° C for 10-30 minutes (the temperature and baking time will vary depending on the make and model of the product and the thickness and consistency the piece).
This process will harden the piece and it may be cut, paint and varnish.

Trademarks and products (source: wikipedia):

"Fimo" is manufactured in Germany and is best known in Spain. It has two varieties: FIMO Classic, it is harder, and FIMO Soft, which is ready for use. Sculpey is also soft as Fimo Soft. You can mix all together if the cooking temperature and time permit.
"Sculpey" comes from the United States where it is very popular.
"Kato Polyclay" is a trademark of United States, owned by the artist Donna Kato with similar characteristics.
There are many other similar marks: "Cernit", "Clay Color", etc.