TubeNet

I have bought an old Amati Kraslice BBb helicon but the neck/mouthpipe is missing.
Do someone know where I can get a suitable neck? Old or new.
The bore is 0.630" (16 mm) where the neck goes.
I really hope someone can help.

A good shop should be able to make you one. Not a big deal.

It's true - get one made. You can probably get one from Czerveny, but that will likely be a lot of hassle.