The Legacy Furnace is a free skin for the furnace based on the original model from 2013. This item was added to the game during the 10 Years of RUST update in December of 2023 as part of the 10th anniversary celebration of RUST as a standalone PC game. Simply play the game for 3+ hours during the month of December to earn your own. The furnace skin will be issued automatically to your Steam Inventory once you’ve met the time requirement.
The Legacy Furnace is used (along with wood) in the smelting of High-Quality Metal Ore, Metal Ore, and Sulfur Ore to convert them to their usable forms. Players may deploy them on floors and other flat surfaces with proper Tool Cupboard authorization.
Prior to more recent updates, furnaces had also been a general-purpose storage container since it had a small, 6-slot storage capacity. Players could quickly toss some of their inventory into a nearby furnace and head back out of the base without a complaint from the furnace. This feature is no longer possible with the Furnace UI upgrades of more recent updates.
In addition to their other functions, standing next to a lit furnace also produces the same effect as a lit Camp Fire, providing 50% default comfort and warming a player considerably. They are only obtained through crafting and are a default blueprint. You cannot cook food in them, no matter how many times you try.