A dolly is a portable anvil used to hold a rivet in position while it is being clenched. It is commonly cylindrical in shape and relies on its mass to work. The act of using it is known as holding up or holding on. It was used also in boat building while clenching nails. See Clinker (boat building). A blacksmith working iron with a hammer and anvil An anvil is a manufacturing tool, made of a hard and massive block of stone or metal used as a support for hammering or chiseling other objects (see forging). ... A rivetted buffer beam on a steam locomotive A rivet is a mechanical fastener consisting of a smooth cylindrical shaft with heads on either end, the second one formed in position. ... Mass is a property of physical objects that, roughly speaking, measures the amount of matter they contain. ... Traditional boat building in South East Maluku, Indonesia Boat building is one of the oldest branches of engineering and is concerned with constructing the hulls of boats and, for sailboats, the masts, spars and rigging. ... Clinker is a boat building technique used for constructing hulls of boats and ships by fixing wooden planks and in the early nineteenth century, iron plates to each other so that the planks overlap along their edges. ...