KELLY'S CRAFTS-Stain Pens. This package contains eighteen fascinating stain pens for use on glass, acetate, plastic, plexiglass, mirrors and even metal. It is so easy to make your own suncatchers. Contents conform to ASTM D4236. Recommended for children ages 5 and up. WARNING: Choking Hazard-small parts. Not for children under 3 years. Imported.