Lego?
Unfortunately, my limited (geographically-constrained) contact with my nieces and nephews has severely impacted my ability to influence them towards technology. :(
Exposure is one thing that is helpful, but in the end, you have to find something that your son is so enthralled with that he wants to pursue it on his own. It begins with curiosity about something, of course, but ultimately requires him to develop the skills and then the confidence to where he wants to begin doing things on his own.
The problem is in the things that parents subject their children to that actually drive the children away from those things... like piano lessons! (I say this as a pianist that has taught many children over the years, and it's obvious which kids are being forced.)
What does he like to do?