In 1945, together with her husband and the engineer Leone Pajetta, she founded BP Radio (later Brionvega), a company specialized in the production of electronic and electrical components for radios, as well as complete radio sets with the Vega brand. Tomasin dealt with the marketing of the products, but after the sudden death of her husband in 1968, she took over the management together with her son Ennio, and he succeeded in the offices of president and chief executive officer.[3]
The radios and televisions produced by Brionvega, had great commercial success all over the world and became known for their particular design. The best designers of the time worked there such as Marco Zanuso, Richard Sapper, the brothers Achille, Livio, and Pier Giacomo Castiglioni, Mario Bellini and Franco Albini. Under her management, the company continued its path of growth and expansion throughout the 1970s.[4]