Hi FJ In addition to the things that John has mentioned Ammo Mig & Hobbyzone produce vertical paint storage solutions for both dropper bottles & jars. Admittedly they are a bit more costly than storage boxes but the footprint is quite small. These can be found, along with other modular storage solutions, at any decent online model/railway store. However if cost is an issue then things you can find at home & repurpose, as John suggested, are as good a way as any to keep things tidy. Cheers