I tried to make a Horse based on the frame system of Dummy13.
I used a horse skeleton as a base and reproduced all limbs and joints. The neck seems to be too small (as you can see in one of the pictures the horse can't reach the ground to eat grass).
There's an adapter that you can slide on the center of the torso part to attach Dummy13 on top. Or put it at the bottom and use it to put it on a stand (maybe using one more neck part).
You can also use this to make a centaur !
Anyway, have fun with this, and if people seem interested I might push it more and even make an armor.
The author remixed this model.
New Horse Frame made by modifying Dummy13's frame