Preflight Inspection
During the preflight inspection, the pilot observed that the hydraulically operated inboard main landing gear doors were in the open position. Although aware that these doors should be closed when the landing gear is fully extended, the pilot proceeded to pump the doors up and then taxied for takeoff.
Taxi and Takeoff
Shortly after taxiing, the pilot received a call on UNICOM reporting that the gear doors were down. The pilot then taxied into position on the runway, at which point the left main landing gear collapsed.
Cockpit Modification
It was noted that the pilot had taped the unsafe-gear warning lights in the cockpit, presumably for night operations. This action may have impaired the pilot's awareness of the landing gear status.