[bpoyner]

Unless you really can switch hands at the drop of a hat (which is incredibly rare), the term is cross-dominant or mixed-handed. I prefer my right hand for fine motor skills and left for gross. I have a coworker is who is almost exactly the opposite.

[virtualwhys]

Exactly, ambidextrous people are freaks of nature, like a professional baseball player who can pitch with either hand from inning to inning, and even then there will be a stronger side -- in other words, it is unlikely that a human being could be equally dominant across both hands.

[yencabulator]

I've literally forgotten which hand I hold a hammer in. Last time I assembled some furniture, I just couldn't figure out any difference. I think I remember there used to be some slight preference earlier, but I just can't say one side would be any better at it than the other.

(I do have clear preferences for many other activities, though which activities go left and which right seems pretty arbitrary, and might just be what I got used to instead of actual dominance. Like, I hold my phone on the right hand because it's in the right pocket, but is that a preference, or just avoiding putting the phone in the same pocket as keys/flashlight/etc?)