A week ago my grandson had a failure of a remote control robot like device; a sad story, but a reason to dis-assemble the entire machine for "parts we can use later!" This gave me the use of a VERY small can motor with a gear on the shaft. I made a hub in plastic that could be press fit on the gear and then attached a 4 blade rotor made from thin but stiff clear plastic, CA glued it to the hub/gear. Tests showed we had a working rotor. I then used styrene sheet in two thicknesses,plastic tube, rod, and aluminum flashing to build the basic chopper body with a bulkhead in the center and a hole on the floor to hold the motor/rotor assembly. Picture 1 shows this.... The second picture shows the complete chopper, the landing pad attached to the roof of the house, walkway, hole in the side of the house for the switch, the battery pack, and switch, etc.