I did not want to order one and wait for it, so I took matters on me hands;
a little pour of a 2k stuff, made for reproducing parts with the help of a silicon mould, I did use cardboart in this case;

and the outcome:

brought to spec (M12 thread) with makeshift lathe...

easy to tap indeed..

a chamfer of the bottom and an o-ring it's all it takes!
