The subject of Castel’s early paintings were scenes of Sephardic Jews in the Holy Land. In 1947, Castel helped to found the "New Horizons".
In the 1950s Moshe's Castel artwork work was inspired by ancient relief paintings depicting predecessors of the Jewish people. These paintings were surrounded by ancient ruins of basalt blocks, which ultimately became the foundation for his unique method.
Castel used ground basalt, mixed with sand and glue, to then mold into different forms that he would engraved. The engravings were derived from numerous ancient symbols of Hebrew culture. The artist produced two major commissions for the Israeli government, consisting of large reliefs in his signature style.