Type metal (properly called Linotype after the machines that used it) was used to make rows of letters used to print newspapers. The machines were operated from a keyboard that the operator used to type in the text required. See
this Wikipedia discussion of a linotype machine for further details.
Linotype metal is an alloy of lead, tin and antimony that is eutectic (has a distinct melting point), melts at a relatively low temperature (464°F), and has enough strength to perform its job. It makes nice, sharp detailed castings that are hard enough to withstand normal handling.