Mattei is a graphic designer and sculptor. Former Professor at the Academy of Fine Arts and in the National Courses organized by the Ministry of Education for Art School Professors, he is the author of the word "Itertesto" (itertext) a word of the Italian language since 1998. The "Itertesto" mark and logos - concerning a new teaching system which is available in the computer version as well as on paper - have been registered which is available world wide. He is a member of the Professional graphic Magistry for aesthetics and visual communication, has participated in international exhibitions in New York, Philadelphia, Kharkhov, Tokyo, Paris, Basel, Brno, Bologna, Barcelona, Warsaw, St. Louis and Milan. He has held personal shows in Italy, United States, Soviet Union, Germany, Spain, Romania, Great Britain, Israel and Poland.