One of the most famous designs is the version created by Colin Farrar which was made using a machine turning process. Unfortunately the part failure rate for the tiny holes near the cone were quite high due to the stresses on the pins that form those features.
Colin Farrar Brewery Services
CFBS is know for their expertise in hand pull pump systems. A key to a good beer is the right consistency head which can be achieved using a sparkler nozzle.
A two part injection moulded alternative was designed, prototyped and tested which provided the beer with an almost identical velvety finish as the original sparkler.
Unfortunately the client did not wish to invest in the new process and the design was never taken on.