Lego and the inventive mind of a 10-year old

My son (age 10) has been inventing things. He is interested in some of the Lego mane guns found on the web (for example here.

So, he has taken this idea and invented his own version, taking the basic idea that it needs a hammer, a magazine, and some kind of resistance (rubber bands). He then decided to try an motorize the thing, because of course it is hard to get any "blow back" for the bolt using only Lego...

The results can be seen here. We will post a short video as well (in the near future.)

Paul