Transforling an animal into a robot with photoshop.
The first thing you need to do is to find a great source image to start with. The techniques of this tutorial can be used on any animal or even human, so choose something to your liking. Try to find expressive and clean image, it is one of the important steps that will ensure great result.
I selected the bridle with Pen Tool and copied it to a new layer before mechanizing the horse. The bridle must always remain at the top layer and the mechanical parts will be place under it.