I have built several gliders from sheet balsa, sheet styrofoam and even sheet foam rubber in my younger days -read, the eighties-. So from my own experience I can tell, everything can become a glider once you get the principles of trimming and dihedral right. And after you get some eye for wing surface and weight, most of them actually fly pretty well. So it's more of a question as to what you want to build and how complex you can make it for kids still being able to make them in an hour. If you get access to plastic props, even a simple rubber model is possible. So the first idea is roughly what do you want to make - roughly- the size you can go and the materials you have.....and what facilities do you have to show it off: courtyard? Second story window for altitude launches/distance records or a meadow with enough space for bungee/winch launches of serious sailplanes.... And then go backwards from there.
And don't be afraid to ask for help in this forum. I for one could probably get you close to a dozen plans for every idea.
So ask ahead.
