Welcome, Ibert4, Effiekins, and charlottemom! We're glad you're all here!
Effiekins, I've got a suggestion for your son: do you know Steven Caney's "Ultimate Building Book?" My lads just love it--it's huge, it explains various principles of construction in great detail, it's profusely illustrated, and it has hundreds of building projects using cheap and easy stuff (rolling up newspaper into long tubes to use for struts, for instance; also cotton swabs, plastic wrap, old sheets, cardboard tubes--basically just raid the blue box!). There's a pretty good preview on Google books (which I never seem to be able to link to--but just search under his name and it should pop right up).
Hope that helps! (I've got one of those need-to-build kind of guys myself, so I know where you're coming from!)
peace
minnie
PS: A couple more ideas for Effiekins:
-Complete-a-Sketch: elementary drafting program for kids, at
http://www.sixbranches.com/CAS0P.htm-some engineering lesson plans, located here:
http://www.tryengineering.org/lesson.php?from=8&to=&cat_id=&keyword= and here:
http://www.teachengineering.org/ and here:
http://teachers.egfi-k12.org/category/lessons/-some fun-looking projects here:
http://pbskids.org/designsquad/parentseducators/resources/ and here:
http://www.sciencespot.net/Pages/junkboxprojects.html-an interesting-looking math curriculum here:
http://www.rainbowresource.com/prodlist.php?sid=1280109929-824964&subject=11&category=6821
