How to Make a Sliding, Self-Locking, and Predator-Proof Chicken Coop Door (2020) (backyardchickens.com)

The article provides step-by-step instructions to build a DIY vertical sliding chicken coop door that can be pulled closed with an external string, self-locks from the inside, and is designed to prevent predators from reaching or lifting the latch. It lists required hardware, explains how to size and cut the doorway and tracks, and describes using either a counterweight (with twine/string) or an alternate spring-lock setup to engage the latch as the door lowers.