A free program for Android, by Javi Pacheco.

Pixel Craft – DIY Color and Pixel Art is a simple art game that allows you to create pixel art with your own 3D printer, or with the help of other means, such as a camera or computer screen. You can create whatever you want, using whatever means you have available. In this case, the easiest way to do it is to print out the image you want to create on paper, then use a pencil or other drawing tool to draw on the paper.

Once you’re done drawing, you can print out the image you created on paper, or save it to your computer and use it as a wallpaper.