Ever thought about putting any of your kids into Community College community education courses? Building minds taking CAD courses gives them an outlet for their creativeness. Our youngest DS 15 is currently in a college credit Into. to Engineering course at school. They used Autodesk's "Inventor" which is way out of the price range of most families, however, if one is a college student they can get the student version for about 10% of the cost of the professional version. The big plus here is learning an industry standard piece of software.
Another outlet might be woodworking...and could be as simple as a block of wood and a set of Xacto knives. Legos are great no doubt but lack the creative touch that free form of carving allows.
