Together with his brother Gianni, Colombo developed the idea of prismatic lamps like the lamp Acrilica(1962). His first design for Kartell was the chair No.4801 (1963–1967) which consisted of three assembled plywood elements. The flowing elements of his chair were a foretaste of his later plastic designs, like the chair universale No.4860 (1965–1967), which was the first seating for adults made of ABS.