Great looking plane, I'd guess he saw you making it too which is great, a bit like growing home veg and the kids know that not everything just suddenly appears in a box or bag in Tescos or big toy store. I made a skateboard ramp ( a mobile quarter pipe) for my son, he got a few years out of it before moving on to the next fad but in those few years he had great fun with his friends on it. I sold it on to someone else afterwards so it's probably still in use.