A basic flathead screwdriver. It actually worked, but as you can see it destroyed the integrity of the tip (as expected). If NASA can make a ratchet, I can make a screwdriver...
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I used 100% infill for the shaft. Needs a brim if you print the shaft standing on it's hex end, or, with a raft if printed horizontal. Printed the handle with a raft, standing on its end, hole on top.