He graduated from the Ecole Nationale Supérieure des Arts Décoratifs Paris, in 1968, after completing the very first course in “ esthétique industrielle ” (industrial design), a discipline that evolved as a branch of architecture. After completing his studies, he and a group of friends cofounded the Design Centre Premier, the first group of associate designers in France. His partners include Xavier Mérigot (graphic designer), Jean Foin (urban architect), Jacques Verger (screenplay writer) and Dominique Prevot (industrial designer). During this time he collaborated with important brands in the fashion industry such as Pierre Cardin, Ted Lapidus, and Torrente. He designed logos for Ted Lapidus and Torrente and perfume packaging for Yves Saint Laurent and Pierre Cardin. In the early 70’s, the long recovery following the fracture of his right foot and ankle due to a skiing accident, along with his passion for skiing, pushed Marc to find a solution to reduce the risk of accidents by immobilizing the ankle. After quite a few attempts, the first completely recyclable thermoplastic rubber ski boot was manufactured.
Between 1973 and 1974 Sadler’s partnership with Italian sports companies in the North–East grew stronger. He mainly worked for Lotto, being responsible for designing all products and logos. Lotto at the time was manufacturing shoes in Italyand was considered one of the most innovative brands, both aesthetically and technically, along with Nike, Puma, and Adidas.
During those years, Dainese, Nordica, Dolomite, Axo, Bailo, Simon, Gipron, Think Pink, Ellesse, Alpine Stars, Nava, Trezeta, San Marco, Selle Royal, Reebok, Nike, and Foot Joy were other very important partners, both in Italy and abroad.
In 1978 Marc started his own business in New York City, creating a new line of shoes for Dainese, leader in the market for motorcycle apparel and accessories. Due to its uniqueness (special sole, reflecting material and polyurethane toe) the shoe became very trendy and was worn by thousands of customers throughout the United States.
In 1983 Marc designed a collection of shoes for Ellesse, also very successful in the United States. These shoes had a futuristic look, techno polymer rubber tips, and featured the company logo imprint on the outside (later copied by several other brands). The Ellesse shoes were not only worn by trend setters in New York City, Los Angeles and Chicago, but by very renowned athletes as well, such as the American tennis player Aaron Krickstein (semi-finalist at U.S. Open in 1989) and basketball player Maurice Cheeks (team member and later coach for the Philadelphia 76ers).
Thanks to the success of the Dainese and Ellesse collections, Marc became known as the most innovative sport shoe designer.
Sadler also designed a shoe for Nike, the first water-repellent thermo plastic rubber slipper, very light and comfortable, that could be worn when taking a shower, still one of the mostly sold Nike products worldwide.
Marc retuned to Italy in the mid 90’s, after having lived in the United States for several years. Although he maintained his partnerships with the sports industry, in particular with Dainese, a company he has been collaborating with for thirty years, lighting and furnishing became his primary focus.
In 1998, Marc designed a scooter, which was half scooter and half motorcycle, for Aprilia. This model was never released on the market and its prototype is exhibited in the Aprilia Museum. In 2001, he designed for Everest a snow board boot lever that works backwards (with a forward flex mechanism), which is the standard system used nowadays.
Sadler has collaborated with multiple furniture companies, as published on his website. During 1998 to 2000 he furnished the TIM (Italian Phone Company) stores, and in 2003 he designed a modular exhibition system used to display perfumes, re-opened the flagship store in New York, and designed the Christmas window decorations for Maison Ferragamo.
As a sample of his design versatility and transversal specialization, in the early 90’s Marc designed a series of orthopedic leggings along with other paramedical supplies for the American companies Watco and Matrix. Marc also collaborated with the oldest family business Beretta and in 1996 he designed a new high technology rifle with plastic components, and a weapon suitcase to be used during sport events. In 2000 he designed a modular electric channel system for ABB Sace, leading supplier of electrical and control equipment.