Difficult tool needed, 3/8 male to 1/4 bit driver, nesting.

[QwikKota]

That is exactly what I want!

I've contemplated 3D printing one, but I'm not sure that even at 100% infill It would have the necessary strength....

I don't really have the time, but maybe this is something I could have metal printed? I've thought about lost wax style casting, but I don't have any sort of foundry

3D metal printing is very expensive and mainly used to print multiples of the same item. What is the torque requirement on this fastener?