The China National Intellectual Property Administration (CNIPA) has published a patent application (CN122343268A) filed by Shanxi Huarui Sheet Metal Manufacturing Co., Ltd., titled “A 3D Printing Passive Powder Delivery System,” with an application date of April 2026. The patent abstract describes a system comprising a printing chamber, a powder recovery unit, an image recognition device, a powder supply unit, and a control system. The powder supply unit is symmetrically positioned above both ends of the recoater blade’s travel path. When the recoater moves beneath the supply unit, the drive mechanism actuates a discharge plate to open the outlet for powder delivery, while simultaneously excess powder is swept into the recovery unit for recycling. The powder supply unit can store different powders, and the recoater can switch between powder types. The image recognition device monitors the powder spreading condition. By enabling automatic spreading, recovery, and type switching of metal powder, the patent aims to improve printing efficiency and quality.