Thanks for the input everyone!
My first thoughts were rectangular boxes because they can be easily stacked up on a shelf...but going with insulation and cardboard tubes sounds like a great solution to my problem (protective, easy, inexpensive storage for stock mouthpieces that came with various vintage saxes I have).
My first thoughts were rectangular boxes because they can be easily stacked up on a shelf...but going with insulation and cardboard tubes sounds like a great solution to my problem (protective, easy, inexpensive storage for stock mouthpieces that came with various vintage saxes I have).