Though originally intended for a more plain, utilitarian purpose, pipe cleaners are a great craft material for the creation of original sculptures. Like other four-legged animals, a pipe cleaner horse is best made by outlining, then filling out, a basic frame structure.
Create a basic "stick figure" to outline the structure of the horse. Twist together two pipe cleaners to create a central "spine" to stretch from the tip of the nose to the tip of the tail, bending up for the back of the neck and down for the nose. Attach four pipe cleaners to the middle section to form the legs. Bend the tips of the pipe cleaners to make the feet.
Fill out the rest of the body's skeleton frame. Twist a few more pipe cleaners around the outline to show where the body shape will have more dimension by making a wider, cylindrical spiral around the center of the body and up around the neck and head. Leave space between the loops of the spiral for now.
Stuff the skeletal shape. Fill the inside of the frame with small, wadded-up pieces of newspaper or toilet paper.
Shape the rest of the horse's body. Tightly wrap pipe cleaners in a circular pattern around the skeletal shape. Start from the tip of the nose and wrap down to the tail (this will require several pipe cleaners, but keep them wrapped in the same direction). Wrap the legs from top to bottom. Wrap the back legs with wider circles to create the shape of the horse's thighs.
Refine the horse's shape. Bend the legs to imitate the shape of a horse's legs (front legs bending forward, back legs bending back, then forward). Shape the head (and nose) by pressing it into place, as if you were working with clay, to create a flared, round end for the muzzle. Give the horse extra "hairs" for its tail by attaching several short lengths of pipe cleaner to the base of the existing tail piece.
Trim any excess pipe cleaner with wire snips.