Want to make your bird feeders more squirrel resistant? Notice I said "resistant" not squirrel proof. One of the first things you need to do is to make sure you have the feeder at least 15 feet from anything the squirrel can use to jump on the feeder, limbs, tables, etc.
We had the best luck with putting the feeders on a T shaped construction of 4" pvc pipe. If you don't want the pvc pipe messing up your color scheme of your yard, Krylon makes a spray paint called "Fusion" that works on plastics. Kinda pricey, but will work. We also put a piece of 12-15" square of light weight sheet metal about 40-48" above the ground and slightly curved the metal downwards.
I am so proud of me. This is the first time I have downloaded anything to a blog. My six year old laptop didn't want to cooperate, but I played around and got it to work.
Now back to reality. this is what the metal looks like. This has been together for about five years, and is not the prettiest in the world, but it works. Now reasons for using this. Don't use hardware cloth or anything the squirrels can get their claws in. They will hold on and climb it. Use the round 4" pvc for the cross piece because if they do jump from a tree limb, etc., they are less likely to grab hold. If you use really small pvc, they will grab around it and shinny along the crosspieces to get to the feeders. They can grab wood. Same for the vertical. You can also spray the pipe with WD-40, kitchen non-stick spray, or a light coat of cooking oil, but we don't use anything with this arrangement.
You have to put the metal about 40-48" from the ground or they will jump up on it, but if you have the downward slope, they are less likely to be able to get to the feeders. We use cup hooks screwed in the bottom of the crosspiece to attach the feeders. We hold the metal in place with lots of duct tape for it to rest on and a little to hold at the top. It doesn't have to be stationary, and is actually better if it is unstable. It was really fun watching the squirrels trying to outwit this for a while, but now they don't even try.
You may want to cap the ends of the crosspieces, or you may have nests of unwanted birds there, or you can use this as extra nesting sites.
It only took us about 7 years to learn to outwit squirrels. We still have lots in the yard, and they feed on the dropped seeds from the feeders, but don't get to the feeders.