The Gee Willikers is easy to build and fly.
You can download the drawings of this RC aircraft model, print them, cut and assemble an airplane model for the evening.
The Gee Willikers has flown, and goes well on two cells outdoors; have not tried it from water yet, still 'splash-proofing' the electronics as well as I can.
This is a pretty awesome little flyer as long as you plan to stick with 65mm props and stay away from using the included prop removal tool included to remove the props