Sew Merry, You are marketing your buttons as supplies, therefore you are not required to test. It is the manufacturer that must test, so anyone that buys your buttons and uses then on clothing designed for children 12 and under must be compliant. Yes, vintage metal buttons may possiblly contain lead, either in the metal, or if they are painted, in the paint. Generally, I don't think most sewers of chldren's clothing are buying vintage metal buttons for their designs to sell. And touching a metal button, even in the slight chance that it contains lead hurt you.