Step 4: Adding color
Going back to the reference image, you are now going to transfer your color placement to the cut out piece of the piranha plant. Think of it like a homemade paint-by-numbers: Designate one color your "number 1" and outline everywhere that colors goes. I chose black, since it determines the placement of all my other colors. Using the permanent markers, fill in the section, coloring 1 pixel at a time. I found this to be important, as large blocks of colors tended to look patchy when colored in sections and not by pixel.
Continue filling in the image using the paint-by-number technique with each subsequent color until your image is completely colored. One important note: if you are coloring in a section using a lighter, more transparent color, such as yellow or red, make sure to erase your pencil grid lines before you do so. Otherwise, you'll see the grid through the coloring.
Flip the piece over and color the second side in the same way. Color both sides of the extra base section as well.