1. According to the size of the door, select the appropriate metal tube and metal plate, and cut the metal tube according to the required length with a hand saw.

2. Choose a suitable round tube material, such as aluminum alloy tube or stainless steel tube.

3. To buy the required processing tools, you need tools such as electric drill, electric drill, saw, file and sandpaper.

4. Cut the circular tube according to the required length, drill holes with electric drill and drill bit, and then trim the surface of the circular tube with tools such as file and sandpaper.

5. Install the manufactured round tube on the furniture to be used instead of the hinge, and fix it in a proper position with screws and nuts.

Please note that the above steps are a general method of replacing hinges with round tubes, and the specific operation can be different according to the type of furniture and specific needs. Before operation, it is recommended to consult relevant technicians or consult relevant literature.