Split your fondant into 6 balls, 1 large one for the body, a smaller one for the head, two for the legs and 2 for the arms. I've put a dessert spoon next to the balls to show scale. This topper will fit nicely on a 18cm/7 inch round cake.
Roll your legs into two sausage type shapes and use a sharp knife to mark the hooves. You could make a horseshoe out of grey fondant for each leg but I was feeling lazy.
Using your clean paintbrush and some water attach the legs to the body. The trick is not to handle the body parts too much or they loose their shape.
Do the same for the arms, attach to the body with a bit of water and stick a toothpick or a piece of raw spaghetti into the body to act as a support for the head.
Next cut a piece of white fondant with the back end of a piping tip and shape it into the snout of the horse. Attach with a bit of water and use the back of the piping tip to form its mouth. Use a kebab stick to make its mouth if you want the horse to look surprised.
Now use the kebab stick to make two holes in the horses snout to represent the nostrils.
Break off two small pieces of brown fondant and shape into cones. Flatten the cones with a ball tool on one end and squeeze the pointy tip to form the ears. Attach to head with a bit of water.
Take a few bits of fondant, make into thin sausages by rolling between your fingers to represent horse mane. Trim to fit the horses head and attach using some water. Use a toothpick to gently seperate the hair and position it on the head. Tweezers also is a good tool for this.