Resin casting is a method of plastic casting

Casting

In metalworking, casting involves pouring liquid metal into a mold, which contains a hollow cavity of the desired shape, and then allowing it to cool and solidify. The solidified part is also known as a casting, which is ejected or broken out of the mold to complete the process...

 where a mold

Molding (process)

Molding or moulding is the process of manufacturing by shaping pliable raw material using a rigid frame or model called a pattern....

 is filled with a liquid synthetic resin

Synthetic resin

Synthetic resins are materials with a property of interest that is similar to natural plant resins: they are viscous liquids that are capable of hardening permanently. Otherwise, chemically they are very different from the various resinous compounds secreted by plants .The synthetics are of several...

, which then hardens. It is primarily used for small scale production like industrial prototypes and dentistry. It can be done by amateur hobby

Hobby

A hobby is a regular activity or interest that is undertaken for pleasure, typically done during one's leisure time.- Etymology :A hobby horse is a wooden or wickerwork toy made to be ridden just like a real horse...

ists with little initial investment, and has been appropriated for the production of collectible toys, models and figures, as well as small scale jewelry production.

The synthetic resin for such processes is a monomer

Monomer

A monomer is an atom or a small molecule that may bind chemically to other monomers to form a polymer; the term "monomeric protein" may also be used to describe one of the proteins making up a multiprotein complex...

 for making a plastic thermosetting polymer.