The free app "My Pixels - Numbers Coloring Sandbox" is an educational coloring book app for children, teenagers, and adults. The app is very easy to use and fun. You can choose from a plethora of images and color them. 

Rest assured that all images in the app are original creations, not copyrighted material. In future updates, you will be able to design pixel art of your own. Overall, My Pixels - Numbers Coloring Sandbox has a lot of interesting activities to keep your brain active and stimulate your creativity.