I mean cut out airfoil shaped ribs, and glue three 1/8 inch strips of paper on top of each other to make spar caps, and have paper skin around it. Make a tail and place a few paper clips in front to get the CG right. Build it with a 3 foot span and 6 inch chord. Use only notebook paper and wood glue. It would be super cheap to make, and very fun too. You should have your kids do a competition with the kids next door to see who can make the slowest stable glide. And make your own, too, to compete with their parent's plane. Calibrate a rubber band catapult or ramp launch so they are all even, though each contestant has the option to not pull the rubber bands back as far as the max allowed under the rules.