The airplane sustained substantial damage when its landing gear collapsed at about 1905 Mountain time during a forced landing. The flight instructor was not injured, but his private-rated student received minor injuries. During a normal takeoff, at about 200 to 300 feet agl, the left engine suddenly lost all power. The flight instructor took control and attempted to feather the left engine but the airplane was losing altitude. He chose an area for a forced landing and headed toward it. Although the touchdown was successful, during the landing roll the airplane encountered rough terrain that collapsed the left main landing gear.