Where do the big snake rack makers get their tubs made?

[misterT]

No one will make you custom tubs, tubs unlike racks need to go through molding process, that mean create a mold and than get the plastic and use the mold to create the tubs. No one will do that for 1 customer needing tubs once.

When people build their own racks or have some made custom they use tubs that already exist either ARS, Freedom Breeder, Vision or Sterilite or Rubbermaid.

So does companies like Freedom, Vision etc mold their own tubs? I see them coming out with all kinds of different tubs like dividers, water cup holders and stuff like that. Or they can do that because they put in giant orders for thousands of tubs? I see how that makes sense. Most of the tubs would work great its just the 6 inch height that makes it hard to find.

Thanks for the response!