Tag Archives: scribble

Invisible ink can be applied to any writing surface for special purposes: pen, stamp, fountain pen, toothpick, calligraphy pen, cotton buds or finger dip liquid. Played with invisible ink, a pen with two tips (one tip is invisible ink and the tip is naturally developed ink). When an object is scanned, the pen mixes inkContinue reading “Does A Color Detecting Pen Exist?”