DAS or DAS Pronto is the trade name of a mineral-based polymer clay currently produced by Italian company FILA.
DAS is an acronym of the name of its inventor, Dario Sala (a poet, author and songwriter), who patented it in 1962. He essentially gifted the patent (i.e. for very little money) to Adica Pongo, an Italian company renowned throughout the 1960s, 70s & 80s for the manufacturer of educational toys. Adica Pongo was taken over by FILA in 1994.
http://www.fila.it/i-marchi/das.aspx