The tiny bottles are great because they don't take up much space, give me an assortment of colors, dry quickly, etc. And, the aroma is definitely nostalgic!
But, they eventually dry out -- it appears the seals aren't intended for multiple openings and closings.
Can I buy similar paints in containers that are more readily resealed? Or, modify the containers so that they seal better (they seem to just have a metalized cardboard "seal" tucked up into the cap)? Or, transfer them to different sorts of containers?
Or, just resolve myself to replacing the individual paint bottles despite how much (hardened!) paint remains within? (this means keeping spares on hand as you never know when you'll go to use a bottle only to discover that it has dried out)