I'm not sure if anyone else has done this, but if you have, it will confirm that my idea was a good one! I just finished my coop and I wanted a way for my wife and kids to tell if the chickens needed more food without having to open the coop, unhook the feeder, open the lid and look into it. Sometimes you just want to get your eggs and get back into the house. I needed something on the outside of the coop to tell them what the feed level was inside the PVC feeder. This would make their trip to the coop more efficient as they would bring back valuable data in addition to the eggs.
I made the feeder based on many different designs I saw on Google images. I made a "weight" to sit on top of the food. The weight would be tied to another object, which would dangle on the outside of the coop. As the chickens eat the feed and the amount of food decreases, the weight goes down, and the object on the outside would then go up, indicating that my girls were running on "E".
Step 1: Rigging It Up
I decided to use weed whacker wire as the string. I didn't want twine or butcher string fraying and getting caught on the wood.
Step 2: Testing Weight
Drill a hole in the cap for the weed whacker wire to slide through. I used a tape measure as a weight for testing purposes. You can use whatever you want, but I would try to make the weight as close to what you really use as possible.
Step 3: Fitting the PVC Feeder Into the Coop.
The next step will be to drill a hole through the wall to slide the wire through.
Step 4: Installing Meter
For the stopper thingy, I used the handle from an old wok that my wife accidentally set on fire. I cut a small piece off of the handle to use. It was light weight and whatever I used as a weight would easily pull it up when the level lowered inside the feeder.
Step 5: Weight Installed
And the water bottle says, "Take a load off, Annie. And you put the load right on me!" This is "The Weight" for "The Feeder"........ awesome! (that's a good song to have stuck in your head!)
Step 6: Secure Feeder Inside Coop
Try to secure the feeder inside the coop to where it can easily removed by your kids. That way they can do all the work! :)
This is a good look at the wire coming out of the cap and going out of the coop through the wall.
Step 7: DONE!!
To mark the levels I just emptied half and marked it, then emptied the whole thing and marked it again.
For a more detailed description of this project visit: http://eighthrising.com/pvc-chicken-feeder-with-meter/
BTW: I've been using this setup for about 3 weeks now and it has worked like a champ. The kids are always letting me know how much food is left.