This may have been mentioned I didn't see any threads referencing this... I was looking for a convenient economical something to put a few drops of paint into rather than the options like artist trays or whatever they are called. I find bottle caps convenient and economical and plentiful for when I hand paint small items. The artist trays for paint too hard to keep clean. I can clean the caps and reuse them and if needed put them in an ultrasonic cleaner for a final touch up. BTW, i don't put them in any kind of solvent like ipa
i have friends who donate their bottled water caps to me.