Color with bold colors hard on coarse sandpaper
Children's art. Color with bold colors hard on coarse sandpaper. All children of all ages can do that. Then some adult guidance.
Turn the sandpaper over and place it on top of a sheet in the color of your choice. (We have used black sheets.) Iron over the sandpaper so that the bold color melts onto the sheet. And voila - we've got a lovely watercolor.