3d model of tacks - Thumb Tac by bikerz

thumbtack (U.S.) (drawing-pin (Br.), push pin) is a short nail or pin with a circular, sometimes domed, head, used to fasten items such as documents to a wall or board for display.

They are inserted and removed by hand.
Some have a colored plastic handle. Thumbtacks made from brass are sometimes called brass tacks. Some are made by attaching a metal stem to a flat metal head.