Experimental designs for prosthetic devices created by e=NABLE volunteers include modular systems with upper limb sockets that accommodate multiple designs of terminal devices (TDs).  Sometimes TDs are created using metric threads (such as M12) while others are created with American Standards such as 1/2 inch fine thread (1/2 - 20).  In order to make modular systems work universally  over the range of TDs, this adaptor can be used.  

Sometimes the volunteer fabricator may not have easy access to the required thread type at the time of fabricating the modular component and this adaptor can be obtained after the fabrication from another e-NABLE volunteer.

Print the adaptor in PLA and use a heat gun or hot water to raise the print to the glass-transition temperature and squeeze it down with a gloved hand to create a tight fit around the appropriate nut and bolt sizes to form an interface between the disparate modular elements.  

The adaptor can be scaled in your slicer if necessary.  

Prior Art:

Monette Socket http://www.thingiverse.com/thing:724815 

Normally-Closed Flexy-Hand Terminal Device https://www.youmagine.com/designs/normally-closed-flexy-hand-terminal-device-1-0 

Flexy-Hand Terminal Device https://www.youmagine.com/designs/flexy-hand-terminal-device 

Hosmer Hooks   http://hosmer.com/products/hooks/ 

Ottoback Hooks   http://www.ottobock.com/cps/rde/xchg/ob_com_en/hs.xsl/5458.html