When I decided to get back into miniature painting, I did some research into different storage methods for paint. I was keeping them divided between two Reaper Miniatures plastic boxes, but it just felt inefficient and awkward. My research pointed me to Battle Foam and their P.A.C.K. system of bags.
I eventually decided on the P.A.C.K. 216 paint loadout bag with three Vallejo paint trays (I use Reaper Master Series HD and Scale75 paints in dropper bottles).