Love this one!
Over the last two years I made a lot of paper aeroplanes for my nephew, after that I started to build my own glider planes and now we're into RC planes.
If you want to get a bit more of a hobby I highly recommend Flitetest community, they made awesome things, and is a great resource to get kids into the hobby.
RC-Plane from cardboard pizza box https://www.flitetest.com/articles/flying-wing-made-from-a-c...
Flite test Steam https://www.ftstem.com/