What exactly are 'plugs'?I will admit one of the advantages I had was I had a chance to get in the big casting shops in Orillia many years ago and see all the original plugs archived (including a couple of ski lift bull gears) and their plug shop and see the production methods.
A bit of research does seem to confirm plug is used with fibreglass or carbon fibre. Sand casting still tends to use the terms pattern and core.
Yeah, about that... No.Plugs, patterns all the same.
Cores are different as they are separate pieces inserted into the molds allowing for more complex internals in one casting.