plain-cm – Vari­able sized fonts in Plain TeX

A font-se­lec­tion sys­tem for Plain TeX, that al­lows users to choose sizes other than 10pt as the base size of their doc­u­ment, and to use ‘rel­a­tive’ sizes like \big, \Big (and so on) as com­mands tak­ing an ar­gu­ment to be set in a larger-than-base size.