The Alchemy Engine is a craftable Science structure. It costs 6 Gold Nuggets, 4 Boards and 2 Cut Stones to craft. The Alchemy Engine is used to prototype tier 2 science items, effectively unlocking the items so that the player can craft them at any time with the materials required. Additionally, Sanity will increase by 15 if the player prototypes an item.

A Science Machine is required to prototype an Alchemy Engine, except if the player is playing as Wickerbottom.