This was inspired by a commercial bird feeder where the design looked good for 3D printing. Unlike a lot of others it only needs a very small support area and doesn't have any small / weak prongs to hold it in place. The design should be suitable for doors that are 77 - 90 mm wide but could easily be scaled to suit other sizes. The wall the wedges between the cage and the door is 3 mm thick so also check your cage can accommodate that. I printed with fairly high quality settings for a smooth finish but it's a simple design that could be printed a lot faster at lower quality.