I saw one in an old post a few pages back that a piece of 3 inch pvc with a 90 degree elbow on the bottom. They attached to the side of the coop on the outside with the 90 degree elbow through the wire and the chickens pecked out of the bottom of the elbow. I will be making one this weekend if it does not rain and try to post pics. I found the post.
I just happened to have some 3" pvc laying around and made one last night. It took about 2 minutes. I will have to wait and see if the rain we are getting is a problem. I will keep you advised.
We had a old rain gutter laying around. My son cut it to size and attached it to the side of the chicken house. he then put a awning over it to keep it dry. The girls love it they go under just to get out of the rain.
I'm using 2" pvc pipe with an 90degree elbow and a "street" 45 degree elbow. This keeps the feed from going straight to the ground. The street elbow keeps the bottom from being to long and allows the chicks to reach in enough to keep the feed coming. The bottom of a P-Trap will work well with bigger chickens too.