Honestly you will get the best results and be more 'bird friendly' if you put up the right bird feeder for the type of bird you are trying to attract.
The most effective feeder is a 'platform' style feeder. You can literally nail a hunk of old plywood to a post or railing, and dump some seed on it, and birds WILL feed from it. Is it pretty? Nope. But you will be able to keep it clean a lot easier that a gazebo style feeder. And the birds are more visible on this type. Plus, there is less bickering between the birds (less, not none).
Next is a 'Hopper' style or 'House' style feeder. I use these more often because they span a gap. Better looking, keeps seed cleaner and longer that a platform, and I can clean it pretty easily. I need to revamp my current one, and give it a good cleaning. Until then, I have not been feeding from it.
Tube feeders will attract tree clinging birds, and finches. These are more squirrel proof than the previous types, but if the seed gets wet, it generally will mold sooner, and you have to clean it more often. Much more difficult to clean as well.
Suet feeders are specifically for suet blocks. They can be attached to platforms or hopper style feeders, or simply hung from a shepherd's hook or a tree. They will attract woodpeckers, starlings (invasive and can be killed, just saying) and sometimes nuthatches. Less prone to mold and whatnot but still should keep them clean for the bird's sake.
Some birds prefer to feed from the ground (i.e. Cardinals). Just about any type of feeder will accommodate this, but if you are on an elevated deck and can't see the ground, this isn't helpful. Fortunately, these birds will also frequent a platform feeder with no roof.
I have a gazebo feeder my step father started for me before he passed away. It is a monster, at about 24" across, but man does it look neat. I hope to get to finish it before too long. Just gotta bang out a few more items on the Wife's list first. It will get used, but I know it will be a pain to clean and maintain.
Hope this helps in some fashion. I know you just wanted plans for a gazebo style feeder, but the next person may read this and find my post useful. The big takeaway is keep your feeder(s) clean, no matter what the type.