I agree with jetdog above, the 5 gal bucket feeders with 90 degree elbows work great. There are a couple topics about them here that show you how to build one or do a YouTube search for chicken feeders.
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Could someone post the link on how to make this buckrt feeder.
Try making one of the bucket feeders, 5gallon bucket with two 90degree elbows you could put 3 but the idea is they can't fling the food out as they have to stick their heads in the elbow, put a little food on the edges of the elbow mine were eating in less than 5 minutes and it holds a month worth of food for my 4 girls.