Okay, the blue containers that we use to ship mouthpieces are perfect for just that, shipping mouthpieces.
Unfortunately, they are not made for daily use.
The foam reacts with your spit and will erode the silver plating. Please use any standard mouthpiece pouch. If you are going to use the blue container remove the foams and use a soft cloth to cover the mouthpiece to protect it from the chemical reaction that can occur.