I designed this tap handle to look like the handle of a Japanese sword for a drink cart that rolls with my Mardi Gras Krewe. Krewe de Fu is a martial arts themed group that costumes and participates in walking parades.
It does not have integrated threads. Instead it has a hexagon hole to capture a standard 3/8" nut which will fit a beer tap (at least all the ones I've seen. I don't know what is standard in other countries). It worked as a press fitting for me but you could also use some adhesive to secure it if it doesn't seem tight enough.
I designed it in Fusion with inches as the units. When I slice it in Prusa Control I have to scale it up 2540% because it interprets as MM instead.
Supports should not be necessary.
Insert a 3/8" nut into the hexagonal hole at the bottom. If it doesn't seem tight enough add a small amount of glue or epoxy and then press the nut in.
Just for fun I'm including a build video of the drink cart bicycle trailer that I made these for.