Then his travels took him to distant India, where he printed maps of the territory of one of the Maharajas on the spot.
Upon his return to Prague, he founded his own workshop. He also continued his studies as a private student at the Prague School of Art under the guidance of Professor Arnošt Hofbauer and painter Václav Jansa. He had workshops in Košíře, Bílá Hora, and from 1939 in V lesíčku Street in Smíchov.
In this intaglio workshop, he collaborated with leading Czech and Slovak artists until his death in 1963. Excluding printers working in art schools, Mirro Pegrassi remained perhaps the only professional printer with his own workshop in Bohemia during the 1950s and 1960s. His nephew, Pavel Dřímal, was the only one among the artistic printers who received an apprenticeship certificate from him.