HI ,
Thanks for that info Christine, I can clearly see from your examples that they have been made to compliment each other and the design employs a cog wheel base to accommodate both parts when together , this is clearly a very sensible idea with the examples you have shown and for the production reasons you mention , but would the original posts piece have been designed with this in mind ,having a plain foot, not too stable upside down with a larger bowl on top in my mind,unlike yours which clearly show the purpose of the design with what is almost a type of locking mechanism for both items to be stable when put together.
Sorry if i sound a bit dumb on this ,as I said completely out of my tiny sphere of glass knowledge
Cheers ,
Peter.