Deckle n. : A separate thin wooden frame used to form the border of a hand mold, or a curb of India rubber or other material which rests on, and forms the edge of, the mold in a paper machine and determines the width of the paper.

Example:
how can I make a mold and Deckle?

Taxonomy
deckle, edge, size of paper, free encyclopedia, soft edge, tear, mould, extrusion, search, free dictionary, belt, woodpulp, vat, sheets, film processing, inserts, slot, coater.

Defination from the web:
deckle is a belt used along with a mold to gather up woodpulp from a vat for pressing and drying into sheets. ... In film processing, deckles are die inserts that set the coating width of a slot die coater or the extrusion width of an extrusion die. ...