Welcome to the Planet, Thomo! Like Nap said, air travel regulations will influence what you can and can't put into a travel kit, and how big it can be.
I have a mobile kit, but it's based on driving to meetups, shows, club meetings, and so, I can carry a little more with me. I have two tool boxes for that purpose.
The first one is a small pine box with a tray that lifts out:
I got this from an art supply store, and originally, it was for my oils. But almost immediately, I packed other paints and some basic scale modeling tools into it.
The other tool box is bigger, holds the rest of my paints in bottles or jars (I don't take any rattlecans on the road), more tools, a portable desk lamp with a power strip and extension cord, my wet palette, sculpting supplies, etc:
For road travel, this serves me pretty well. Unfortunately, I can't speak to packing for air travel.
Hope that helps nevertheless!
Prost!
Brad