You could find and umpa loompa doll and a barbie doll and recreate Marine Force One quad edition... you could do Snoopys dog house and fly against the red baron...
You could also finish the light project with them fancy led's from last year by mounting a motor underneath the quad to spin a disc the led's get mounted to instead of trying to fly around on full yaw.
Maybe take a gremlin sized build and design a soap bubble mechanism so it creates tons of bubbles for the little ones to chase around.
Can make a carbon tube sphere around one and do quad bowling.
Maybe find a funny use for the spaceship 3d hexa you made.
Build a plane with an inverted bomb bay so quads can be launched and recovered mid air. Then have the plane drop a few parachute army men and have the pilot of the quad hook them and bring them back to the plane.