I did a fair amount of drawing, too. I have a page, which documents the proportions of the head, chest and flank, another, which documents the construction of the head, and several pages dedicated to the proportions of the legs and how they move. Having those as references speeds up my drawing time considerably, but they're imperfect. The hardest things to figure out were the front legs. Unlike real horses, the FIM ponies have extremely articulate shoulders, which sometimes "break" their anatomy. For example, take a look at this picture from the show of Bonbon (and Lyra) sitting: Bonbon's shoulder is sitting really far back and pretty high. It's not super noticeable because her neck is bent forward, so it's hard to understand its position on her body. The solution I figured out is this: These legs are roughly the same, but in different poses. The blue circle is her chest and the blue dot is the center of her chest. The joint, which rotates around the blue dot, is the equivalent of our clavicle, which allows our shoulder joint to move in a similar way. Considering these aren't real horses I can accept their more flexible anatomy, although it took a while to figure out how it worked.