Zokissima, came across a trick from my friend who is into water colour painting, he uses oasis' the type you can soak in water and stick flowers into, as in flower arranging,
He uses little jars of colour, and pushes them into the foam, and keeps them in cigar boxes scrounged from the local tobacconist, needless to say, I have taken up the same, labelled the boxes with a dymo and colour groups eg Luftwaffe Armour,RAF USAF etc,
the boxes are free(thankfully) and the oasis' cost about $2-$4each dependant on size, just an idea.
Nick