If I were to be travelling and away from home for a few days, then I would probably carry the following as shown in image below. I created my small sketch book specially for carrying it around as it is very convenient to carry. It is a different issue that I have already started using it while at home as I am loving my experience of creating mini water colour paintings.
The Image above shows the following
My open box palette with all the essential colours poured in it from the tube
Closed box palette
My water colour sketch book
Few water colour round brushes
( As of now I have been using round brushes by Camel and Arora )
All the three things as mentioned above are light weight and very convenient to store as well. Given an oppurtunity one can easily paint a few water colour sketches while away from home. I definitely plan to do that some day.