I've long had trouble with transporting a coqui with a conductivity sensor for demos. Remembering to bring cups, and salt, finding water near my demo site, mixing a saline solution to demonstrate what the coqui can do, and trying to not spill the water all over my table of electronics with a bunch of people around. It can be a lot.
Had an epiphany this morning-- use a contact case! Fill one side with water, and the other side with saline solution. The difference is audible, there's very little water so less spill risk, and you cap it to take it with you.
Just thought I'd share!