Molds can be as simple as pressing the part into the ImPRESSive Putty or pouring ComposiMold over your part. Molds let you duplicate your creations into different materials. Into real parts. Learn more by going to a specific topic:
Mold Making Basics
Mold making is the process used to duplicate three dimensional models. Through the use of a mold making material (or mould making if you're in Europe) a negative of a model part is made. That negative can be used to cast a second part that is identical to the original part in size and shape. The same mold can be used to make duplicates of the original Master parts.
And ComposiMold and ImPRESSive Putty are re-usable molds. You can re-melt and re-use as many times as you want as long as you don't overheat the mold making material (boil it too many times). There's no better product for making molds without wasting molding materials and getting great results.