Vintage copper molds are highly collectible among enthusiasts of antique kitchenware and baking tools. They were commonly used in the late 19th and early 20th centuries for baking cakes, breads, and other desserts.
Miniature copper molds, such as the one you mentioned, were often used to make small, individual desserts. These molds were typically made of solid copper or lined with tin, and were designed to withstand high heat and to be easy to clean. These butterflies are 3.75 x 1.75 x .75