Crayons, colored lead, pencils, fountain pens, gouache pigments, acrylic pigments, poster colors, gouache pigments, writing brushes. Uncle Neil said that knives, forks and spoons can be used to draw pictures. There are also sand, salad oil, food coloring, olive oil, detergent, some colored particles on washing powder, shampoo, shower gel, hand sanitizer, toilet water, milk powder, drinks, cream, butter, jam, tomato sauce, Chili sauce, banana, strawberry, grape, pomegranate, watermelon, cantaloupe, durian, apple, pear and so on. And cucumbers and things like that. Make your own coloring tools, for example, you can rub a long strip with a paper towel to make a writing brush!