Air foils. I put two in here, primarily in the "print and be amused" category, but there are some legitimate tests one might try with these:

* Mirror the hollow wing and glue them to a lasercut balsa fuselage to see if they work at all.
* Stretch some kind of airtight fabric over the frame, clip to balsa fuselage and see if it flies.

However, I must advise that anything printed in a ten-centimeter cube is going to be fighting the square-cube law pretty heavily, so even my nigh-gossamer wingfoil may just not be able to get up lift.