Oh, look! I made a thing!
https://www.printables.com/model/1227667-underware-compatible-connectors-for-goews

Printables.comUnderware compatible connectors for GOEWS by joncruz | Download free STL model | Printables.comA set of connectors to allow hooking up Underware system items with GOEWS. | Download free 3D printable STL models