I've had in mind to contribute to this thread for awhile, finally getting here.
As far as specific opportunities to do something real - I recently heard about
the Connecticut Corsair restoration project. (The page looks old but this is still going on.) From what I've heard, which is secondhand, they are giving kids the chance to help design parts. (SolidWorks was mentioned as a package they use - this is real stuff.) Worth looking into if you've got kids who are interested in aircraft or design.
Several families that I know have their children help out at the same workplace as the parent(s). It's not always child-driven, but I think it's still useful for kids to contribute in a workplace and see a little bit more what work is like. The folks I know who do this all work at, and/or own, small engineering firms. When the company needs help on some appropriate task the parent asks if the kid(s) would like to do it or help. Usually not very exciting (eg assembly or packaging) but the kids are often eager to help out.
Back when I worked full-time, I often added several high school & college kids to my group in the summer. Parents in the company I worked for would come see me in spring about summer jobs for their kids. Thinking about it now, I should probably have treated it more like summer camp.