Here's How to Design a Squirrel-Proof Bird Feeder
This might work for now, but an update will be needed when the squirrels figure out how to use tools.
Squirrels are fuzzy, cute, and fun to watch, but they can be a nuisance when all you want to do is feed the birds around your neighborhood but those pesky squirrels eat all of the goodies in one go. Trying to stop the squirrels might feel like trying to accomplish the impossible, and in all honesty, getting rid of them completely sounds like a far-fetched dream; however, with a bit of interesting engineering, anything is possible.
In this video, the YouTube channel Chris Notap explains how he designed a squirrel-proof bird feeder by getting some help from the squirrels themselves who readily volunteered to help him determine their limits. He had to find what size of opening a squirrel cannot get through, and in the end, he achieved a bird feeder that makes sure birds get the lion’s share of the seeds. It's possible that the squirrel's next visit will include a hacksaw and screwdriver; however, for the time being, the design seems to suffice. Enjoy!