I have a couple of cases that I use. Here is one that does not have removable wells. It is an airtight container and I really like the large well sizes.
I like Daniel Smith and Shinhan tube watercolors.
I just got this small metal travel case:
It holds THESE half pan plastic watercolor palettes.
For both cases, I fill them with tube watercolors. You squeeze in the watercolor and let them sit to dry. They dry solid after a few days depending on your climate.