4/5 of my girlfriend's have been ISTPs, idk if it's because they're simply overly common than our lovely INFJs that we want, or it's because their Ti is attractive - albeit with the Se sideline. Anyway, a girl I'm seeing now noticed it yesterday, I already knew it, but she was like "we're different in thinking...I like to have more 'concrete' or workable ideas and you're more abstract/theoretical. So yeah pretty much.
My dad is one. Engineer, doesn't mind never leaving the house, rides a motorcycle, enjoys basketball/sports. Stubborn. Very stubborn. Hard worker. Very intelligent but sees life in quite a simplistic way -- cannot relate to the existential crisis state I was born with and likely will die in.
This is how simple life is for him: he enlisted in the Navy when he was 18, did so well on entrance testing that he got his choice of technical training, traveled around and partied and built a future career path for himself through education/experience. When he was discharged he told his friends that he was going to move to California and marry the first pretty blonde girl he met. And then he did. And they're still married, because she is an ISFJ (and a Catholic).
I've known a couple of other ISTP engineers as friends and their sureness of themselves/their decisions, need for (comparatively) very little in life to be happy, and ability to enjoy simple pleasures and be in the moment is enviable. But the tradeoff is that they can be closed-minded and a bit arrogant because of their intelligence combined with perceiving in such a literal fashion.
I have an internet friend who has built me a couple computers. xSTP. Says he loves to do it and the proof is he doesn't charge me. I just pay for parts which he loves to talk about. I have to be careful I don't get too theoretical with him. He likes to get things done which makes theory kind of worthless anyway.
ISTPs are very helpful to have on hand when building something: They are to the physical world what we are to the mental one. I remember buidling a Rube Goldberg machine with three ISTPs for my physics class, and while I handled most of the higher-up thinking, oversight, and math, they handled the tiny nuts-and-bolts sensory details that would have otherwise made my head explode in overloaded frustration.
While they had enough Ti to have succeeded without me, I hasted our work by letting them focus on one part of the job. Technical drawings in black marker on the back of a pizza box? Done. Trig calculations to back those drawings up? Did that while doing the drawings. Envisioning mechanisms that will wow a crowd, and then architecting them while occasionally helping out with the smaller stuff? With relish!
Ti: Models everything with razor-fine precision so that models can simply be worked from instead of 'interpreted'.
Ne: Possibility identifier and imagination powerhouse. Chameleons to Se for ease of socialization.
Si: Routine task handler, special information gatherer and storer.
Fe: Bond and feel proud of helping others and be glad that I'm working in physics.
Physics projects. What an unusual place to feel actualized.
My mother and two younger brothers are ISTPs. The youngest is the only one I can have rational conversations with, probably because I had so much influence in shaping his personality (not fucking him up like the other two)... Otherwise I have barely known any
My brother is an ISTP. The guy is basically an action hero. He's a firefighter, in the military, flies helicopters, is a very good surfer, rides motorcycles, etc. He has no interest in theory and strongly dislikes anything academic. He goes out, saves people's lives, and gets his adrenaline rush.
He builds things and he builds them well, but, due to a lack of design beforehand, they tend to not look as good as they could. Everything looks good on its own, but much of it seems a bit out of place when taken all together. What I mean is that he lacks a view of the bigger picture.
Sorry, but I just don't like when someone tries and instruct people how to type... There's too many variables! But it's true that the body, especially the face, and more especially the eyes tells you a lot...