From 1953 to 1960, Colombini was the technical director of Kartell, which was founded by Giulio Castelli to produce plastic injection moulded products.

Kartell produced modern household appliances that were distinctive and colourful, which represented a complete transition from the typical utilitarian aesthetic of the 1950s.

[1] Colombini designed many household products for Kartell that were revolutionary and affordable examples of everyday items.

His products include a carpet beater (1957), a lemon squeezer (1958), plastic wash basins, salad colanders, lunch boxes and a long-handled cleaning scoop (1959).

One of his most famous designs is a round umbrella stand made from ABS plastic with a stainless steel ashtray top (1965).