Antique machine parts such as cast-iron gears, glove molds, metal pulleys, and wrenches are prized for their sculptural shapes. “Though they may have been created for factory use, these objects have a Shaker-like purity of form,” says Maine dealer Lew Alessio. Here, an early 1900s wood gear mold ($395) sits atop an 1890s cast-iron pulley ($250), turning old machinery into a decorative art collectible for your home.

Prices: $35-$500.

Good buys under $100: Broken pulleys from a working barn might be found for about $25.

Dealer’s tip: According to New York dealer Leslie Segal, you should buff off excess rust with steel wool, then polish with wax or mineral oil.