In 1971, a patent, US3596285 was issued for a Liquid Metal Recorder, a printer process that fabricated metal models of symbols, patterns and characters. Liquid metal was referred to as hot-melt "type" ink in this patent and it was introduced before the term 3D printing was ever conceived. These are examples of inks that create a 3-D effect on the page.
In 1971, a patent (US3596285) was granted for a Liquid Metal Recorder, a process that used liquid metal to create three-dimensional models of symbols, patterns, and characters. This invention predates the term "3D printing." The ink used in this process is referred to as "hot-melt type" ink.