I needed to fill the space that would eventually be the belly of the horse. So, using duct tape, I made a temporary reservoir for the foam I'm going to use to fill the space.
While I'm waiting for the foam to harden, I start to work on the horses other end, his head. I framed in the upper part of the muscled neck. This just helps me to visualize.
The following photo's show the progression of the horses skull, while using a real horses skull as a guide.
I fine tune the shoulder bones. Have to. The muscles attach to specific parts of the bones in the shoulder. I'm not trying to get an exact shape of the bone, just a sketchy form of the shoulder. Here I've started to construct the shoulder's muscles on the right side of the horse.