DS9 (Yes, NINE! He had a birthday on Friday!) is an extremely hands-on learner, who loves to build things. Legos, models, puzzles....you name it, he builds it. He wants to be an engineer, which I think will probably be a good fit for him. Problem is, I can't keep him in stuff to build! I got him a k'nex roller coaster set. He put it together in a couple of hours, decided that he'd had enough, and used the pieces to build a launch tower for his lego space shuttle. He puts the 14 and up lego sets together in no time at all. I bought him a set of model rockets (Mercury through Apollo program) for his birthday, and he has all of them almost done already. He builds and launches rockets - which he enjoys, but again, it seems like it takes no time to do it, and before we know it he's bored again. Does anyone have any ideas for projects he can work on (either things I can buy him, or do-it-yourself type things) that will be both challenging and interesting to him.....and take him long enough so he's not done with it by the time I get the wrappings in the trash can?