Nicknamed "clankies" in the collecting community, metal models come in a wide variety of sizes, styles, and metals. "Pot metal" is a common base metal for many model horses, which are often plated with prettier metals like copper, bronze or chrome.
In the 1950s, metal horses were common prizes at carnivals, with different sizes and colors of metal (gold, silver, bronze) signifying different prize levels. These horses were inexpensive to make, since pot metal has a low melting point, so it requires no special forges to cast. Pot metal is so-named because it was made from whatever metal scraps got thrown into the pot, commonly some combination of zinc, aluminum, lead, iron, tin, copper, etc.
Other metal horses are made of solid brass, bronze, copper, etc. Some are painted or coated in enamel, and some even have inset crystals or jewels for sparkle.
Some models can be quite detailed and expensive, while other models remain affordable to most collectors. Whether you collect clankies specifically or just want to add a few to your collection because they catch your eye, they will add a glimmer and shine to any display.