Hi I live in Sweden and the downside of living in such an environmentally conscious country is it is illegal to have oil-based paint, even for your home. They want everyone to use waterbased paint so I was buying my oil colors in the US and taking it back in my suitcase. however, getting the solvents is very difficult--you pretty much have to buy it in a neighboring country and drive it over or risk putting it in your suitcase and having it confiscated.
Thus, my advice is to travel with waterbased media that is clearly labelled as such. Ignorant security people will sometimes still confiscate material. another way I travel is to take smaller tubes of the water based media and put it in my makeup case---apparently they don't scrutinize cosmetics as much as something that looks like tools or 'equipment'. the same for palette knives.
another option if you are travelling to a workshop abroad is to ask if they will provide materials or can arrange to have a kit for you. then you travel with your favorite brushes and a good case to carry back all your work, less risk and much lighter.
lastly, if you are travelling in a car- or by train-you can pretty much pack whatever you want...just arrange to ship your materials in a case and buy the questionable stuff locally-such as turp, aerosols, etc.