[raspasov]

When I was a kid I had a number of Lego Technic sets - they are great! Might not be proper "engineering" but still allows you to touch and build a simplified version of many real-world things, for example a car's drive shaft.

http://www.amazon.com/s/ref=nb_sb_noss_1?url=search-alias%3D...

If he's already pretty skilled, he'll definitely be able to handle even the sets that are marked 10 years old +. I recall I had one of these when I was 6, it was a slight challenge but that was the fun part : ).

[orless]

Yes, he handles 9+ pretty well. He's now playing a lot with Fischertechnik (http://www.fischertechnik.de/home/produkte.aspx), it's a German analog of Lego Technic (or vice versa, whatever), but as far as I can tell it's somewhat closer to reality. I'll take a closer look at Lego Technic though, thank you.