I'm not an engineer (I'm actually a geologist though, so similarly science-minded instead of arty). As a child, my teachers would tell my parents that I needed to socialize more, and then I had to endure a whole bunch of contrived play-dates with kids I had nothing in common with.
I was always a member of guides though (Girl Guides in Canada, Girl Scouts in the US). I found that I met more friends growing up, in guides, than I did in school. We got to go outside, hike, swim, camp, and get dirty, which was infinitely more appealing to me than playing with dolls, for the most part, or reading fashion magazines as a teenager. I was also a member of 4H in my teens.
I was a still a little behind on my social skills when I started university, compared to others, but I'm 30 now, and I have caught up without much ongoing effect.
I would recommend some sort of non-school activity, wether it be something outdoorsy, like scouts, or an organized sport (I also played baseball as a teenager). Please don't subject your son to manufactured play dates, they were the worst. I also hung out with my cousins a lot, and we would either do stuff outside (like build forts/toboggan) or play video games.
There has to be more sciencey kids out there for your son to socialize with, you just have to figure out where they are, and what activities they are in.