Those doodlebug breakaway moulds look the business. Pity they are showing out of stock at the moment.
I plan to come back to them at a later stage for another look.
The Namix ones are also interesting and available now too.
I'm not sure I like the adjusti type as much as the other "bomb" shaped ones, from a casting point of view I mean.
The shame of it all is a long time ago I bought and had my own full set of machined aluminium Aquapedo moulds from 3 to 8 oz, they even had hollowed out backs so they could be pre-heated easily and never got blocked nozzles. I lent them to a "pal" once, never saw them again. Well we all learn!
And I see Veals have a Varivas mould in 5 and 6oz which seems to be similar to the Namix.