He met Spoerri in 1949 and Klein and Saint Phalle (who later became his second wife and great collaborator) in the 1950’s. Christo, Klein, Arman and Saint Phalle were fellow-members of the Paris-based Nouveaux Réalistes. Breer and he planned an exhibition of motion in art while sitting on a rooftop in the night-time rain, he collaborated with Spoerri, Kienholz and Rauschenberg, and attached motors to Klein’s paintings in a joint show. Duchamp and he were mutual admirers, while Rauschenberg, Chamberlain and Klüver met and helped him when he stayed with Huelsenbeck in New York.