This is the one my husband made for us, it is a continuous feeder so we only have to put the feed in it once a month or less. We use pellets though not sure if it would work for mash, I've never used or even seen layer mash.
https://www.backyardchickens.com/forum/viewtopic.php?id=605462
https://www.backyardchickens.com/forum/viewtopic.php?id=605462