My younger aspiring geek, age 10, took apart one of his Nerf guns yesterday, and was able to reassemble it successfully so that it remains fully functional.
Today, after he and his brother got some spray paint, he took the gun apart again, and then spray painted some of the parts with his own custom design. He re-assembled it and it looks quite good!
He did, however, learn the lesson that even when spray paint is dry to the touch, it may not be completely dry. The slide on the gun ended up stuck, so I had him take the gun apart again, to let the parts dry more thoroughly.
Very proud of his efforts though, and I have a feeling there’s more customization to come. I’ll post pics once he’s got it reassembled again.