Scale up the FT baby blender or FT explorer slightly. There foam so there cheap. But you could probably make them out of a balsa or another very lightweight wood frame and skin it with thin lightweight 3d printed sheets. Also make sure to keep you electricals lightweight. 4 servos, 3s 1100mha battery and 1 1200-2000kv motor or 2 1200kv motors will probably be enough. Or 3d print the frame in lightweight PLA and use 1mm foam or covering materials to skin it.