A pin is a device used for fastening objects or material together. It is usually made of steel, and is formed by drawing out a thin wire, sharpening the tip, and adding a head. Pins are thin (usually metal) rods that are inserted through holes in supports in order to fasten the supports to a part or component. Types include ejector, knockout, bridge, side-draw, and center.

Shafts are pieces that are used in movable structures and that carry torsion stresses, as in rotors and motors. They can also be a vertical load bearing structure that uses end bearing and friction to support loads.