To extrude is to form the shape of an object by forcing plastic media (a "blank") such as clay, wax, plaster, or dough through a die. Extrusion is the process of forming three-dimensional shapes in this way; or it is any product of this process. Lucky Charms cerealSome pipes, tubes, and other objects are manufactured by extrusion, as are such culinary products as certain breakfast cereals (see thumbnail to leftLucky Charms?), pastas, cookies, and candies. Bakery workers often decorate cakes by extrusion ? squeezing or "piping" frosting from conical bags with variously shaped openings at their tips.Hasbro's "Fun Factory" is a tool for extruding Play-Doh? through strips of plastic dies. Play-Doh is a modeling compound with similar physical properties to clay, but it is not actually ceramic.Once a pug mill has mixed water with dry clay, it extrudes the product through a round or square opening. Viewers are apt to compare such extrusion to excretion. (Such observers may be indiscrete [infantile?!], diverting attention from loftier goals, but excrement is a product ubiquitous to creatures with digestive systems.) One crucial extruding plasticdifference between these processes is the greater potential in extrusion for varying the shape of the product.Although wire is formed by pulling ever-thinner strands of metal through dies, this action is typically termed drawing rather than extruding.More liquid media ? paint, glaze, and slip ? can be applied by forcing it through small holes, using a squirt bottle, syringe, or spraying device perhaps, but its formation is unlikely to be termed extrusion. A resulting mark ? dot, line, wash, mist, whether dragged or smoothed across a surface ? will be largely two-dimensional.Also see hot glue gun, mold, and set.