Modeled up the end of of the 1.875 shop vac hose for the purpose of designing tools for it. The threads on the end have not been tested but are modelled to match the best I could. Threaded and Unthreaded versions available + the F3D model is there if you need to modify to suit.
This is the MALE part of the joint, you will need to design your own part and subtract this core shape.
The author hasn't provided the model origin yet.