Print one each of the lens cap, door, and spring at .2mm or better. Slide the spring into the cap from the inside toward the outside so the spring lays flat on the cap. Note you will need to raise the middle of the spring above the little post in order to get the other side in. Slide the door over the spring so the feet align with the holes in the door holder, and you're done! If the door won't fit, you may need to file the feet down slightly.