Double Square drive adapter. For sizing at present, proof of concept and materials testing. PLA will not be strong enough - probably.

Additions to come:- For 3/8" hex drive (i.e. standard ratchet) 10mm shaft drive (i.e. for drill chuck)

Edit 12/05/21 Final double hex drive files added for socket drive and drill drive. For use on boat winch.
it's just a design project, it will work on a very light load with pla home print. The design may help in the manufacture of something more up to the task. Not progressed with any further testing.