Only the unequal-span biplane wings were inherited from the L.2; a new and refined hull and strut-mounted tailplane were designed.

Like its predecessors, the new plane was powered by a single Isotta Fraschini engine strut mounted between the two wings and driving a pusher propeller.

Over 200 M.3s were built and delivered to the Royal Italian Navy and were used on a variety of missions which including bombing, reconnaissance, patrol and escort.

In 1919, an L.3 which belonged to the Italian Military Mission in Argentina connected Buenos Aires with Asunción, Paraguay for the first time.

A number of second-hand aircraft were used by the Swiss company Ad Astra Aero to carry out charters and joy rides on the Swiss lakes, the two passengers were seated side-by-side behind a large windscreen with the pilot in a raised open cockpit further aft.