A favorite for craft and art projects, Sakura Souffle pens feature a unique 3-D ink that leaves a pastel-like raised line you can see and feel! They can write on regular paper as well as non-porous surfaces like plastic, glass, and metal. They can be used on white or colored paper, and their colors stand out particularly well on dark surfaces. The ink is waterproof on most surfaces, water-based, odorless, and AP certified non-toxic.