I created this plug to mount a standard tap on my wooden rain barrel. It connects with a screw thread which has standard measures (at least in the Netherlands) of BSP 3/4" (=27mm outer diameter). The plug is tapering from 39 to 36mm such that is can be firmly pushed or hammered into the hole.

I included the scad-file so that one can easily change the plug diameters. The screw thread can be changed as well, but you should be more careful what to do.

There is no need for supports. I printed it using only 10% infill and it was solid enough for its purpose. The result was a marvelous solid and waterproof connection.

I added the Gardena connector to attach the hose to the barrel. It did fit in my tap, but it was taylor made for that purpose. I included the scad-file as well, so you may create your own connector if this one does not fit.