Coloring bitmap excavator
With great interest the boys look like the technique works. A backhoe is something mind blowing. When pulling the bucket, he draws the earth. Then the blade rakes dug trenches. And it works like a transformer in cartoons. This is not a luxury car, but as the digging! By playing with the technique can be coloring your excavator and to dream, as he would dig a huge pit.
Coloring in a raster (pixel) format. If you use a graphics editor such as adobe Photoshop, then using the fill can easily paint a picture. Outlines for coloring perfect to spend some time coloring on the computer. For children this can be fun and not an obsessive study of the work in the graphic editors, and knowledge of the world in different shades and colors.
Coloring can be printed, and then paint.