It’s not like etching with hydrochloric acid and peroxide is anything new ... or that ferric chloride is far safer and cleaner. It seems to us that most of the naysayers are somewhat overwrought ...

If necessary, protect non-glass surfaces of an overhead projector with clear plastic. Dip one Q-tip into concentrated hydrochloric acid (HCl) and a second cotton swab into concentrated aqueous ammonia ...