I can only agree with the comments made on the paints and brushes so far, but my personal paints of choice are Vallejo Game and Model colour.
I do a fair bit of traveling myself too, and spend the night at many a hotel. And let's face it; those bars all look the same, and are only fun if your favourite passtimes are drinking and/or people watching. So I tend to take some painting work with me every time.
Problem always was to:
1) lug the stuff along undamaged
2) get the stuff through customs and (airport) security without problems
3) be small enough to fit into carry on luggage
4) take every single thing required to paint
Now, my trips usually last from one night up to about a week, so I don't have to take my entire collection and equipment with me; just enough to last me for a maximum of 5 to 6 nights. And usually, I don't even get to that number, as there will always be some function, or social obligation, taking up one or more nights.
So, a couple of years ago, I received two free cases, containing some complementary car safety stuffs from a car insurance company. And since I pretty much have all that gear in our cars anyway, I put them to better use.
It's these small plastic cases:
I first only did the one, but that will carry just the painting gear and one or two minis.
Here's my proof of concept, made with some cardboard:
And here's the finished product, made from 1mm thick black plasticard, simply glued with polystyrene cement. I made the contents modular, so I would be able to switch out parts, if there was a need. However, I've found the current setup to be sufficient so far:
This is the most important part of the case; the paint rack. It holds 15 dropper bottles. If you were to use up the module on the right to hold paint as well, you'd get up to 24 dropper bottles in there though:
The module on the right is designed to hold several pieces of equipment, such as a mixing tray, some cloth, a cork to hold pinned miniatures etc, in the top section, and one or two minis in the bottom section.
Top section:
And the bottom of the top section, which is coated in foam, to protect the minis in the section below:
Then the bottom section, which is just a foamclad tray for the miniatures:
Finally, there's the module that fits into the curvature of the case. This one does not have all that much capacity, but it's perfect to hold brushes and other tools. I tend to not take any files or blades with me, because of security reasons. This is also the reason why I exclusively bring along assembled, cleaned and undercoated miniatures; so there's only paint required.
Also, the wider parts of the module can hold a flip top bottle of GW design each, if I really have to bring a specific colour in such a bottle. I always pack some more cloth on top of the brushes by the way, to stop them rattling around in there:
But I found that that's not enough for longer stays, so I then converted the other case into a dedicated miniature carrying case, using some KR MUlticase foam trays I bought for that purpose. They fit with very little problems, I just had to adjust the shape of one of the rows to match the curvature of the case and presto!
It was a simple matter of marking out the contours on the bottom of the foam trays, cutting the dividers down into shape and then reglueing the outer edge back onto the shortened dividers.
I have one for smaller individual infantry type miniatures, and the other tray is for larger miniatures. In order to prevent the minis form the top tray to fall out when I open the case, I added a foam divider, held in place by some repurposed shoelaces, which I simply push inbetween the foam and the case wall.
As long as you don't have too many large metal minis in the top lid, the laces and foam are perfectly up to the task of holding the minis in their place, even when opening and flipping open the case.
I actually use that particular case to carry miniatures for skirmish games or Bloodbowl for instance when going over to a mate's house for a game. Much easier to handle than a full sized carry case!
And finally, here's a shot of the cases in use in a hotel room, earlier this year:
Back when I made these, a friend urged me to get my plans lasercut and sell them online. I still might, but with this, the cat's out of the bag, and I will probably never get around to do that anyway. So instead, I hope it will help you...