Guided tap wrench

A neat solution
https://youtu.be/sC9lWrQeNX0

Thanks for your great idea
Where did you obtain the tap adaptors that you used for your design

Elegant. Well done.

3/8" tap adapter
https://www.acmetools.com/shop/tools...dapter-3095001

The other fix that could have been done, to make the T handle a press fit, is to distress the 5/16 rod with a center punch, or small chisel punch where you want it to be fixed in the hole. I've seen this on many tools, including several of my lathe chuck keys.