Discarded objects you need to build a bird-feeder:

• 1 bottle (with the label removed so that nobody votes just for my great taste in beer ;))
• 1 soda can
• 2 plastic grocery bags of any color (I used tan and blue)
• optional twist-ties.

Also, you need some bird seed, if you want birds to actually visit your feeder.

Why a bird feeder for this task?
I love birds. And beer. And diet soda. (Well, I don't love diet soda, but it's all right. And tea's not always convenient.) I go grocery shopping a lot. In fact, I could make a heck of a lot of these things, if I had the patience. ... I wonder if this is on the right side of the line between "Man, she's too cheap to buy me something?" and "What a thoughtful home-made kitschy present!" It's a lot of work to make one, but I think it's kind of the awesomest thing ever. It probably depends on the recipient of the gift and just how "green" and pleased by hand-made things they are.

Also--and this is important--screw-top bottles are totally useless and make me unhappy. I definitely needed to find something to do with these things, for my own sanity. (I can reuse the pop-off-type bottles, since they can be re-capped with homebrewed beer in them. Screw-off bottles aren't recappable, at least not by the likes of me.)

A rough idea of how I went about making this:
So, what have we got, here? Well, the plastic bags can be cut into long strips and braided to make some stretchy but fairly strong "rope." The rope around the spot where the neck and the body of the bottle meet was made with the handles of the plastic bags, since it had to be extra strong. There are two "hangers," one in tan and one in blue, which each fasten to two points on the strong center-rope. The rope around the top of the bottle is just for stabilization; without it, the hangers would slip and the bottle flip and all sorts of badness would occur.

I was running a bit low on plastic bag by the time I had all of that part done (if I wanted to stick to "2 plastic bags" and not up it to 3), and to be completely honest, I was getting a bit sick of braiding. That's why I didn't use this "rope," but merely some single strips of plastic bag, to hold the feeder cup on. When this feeder has to be repaired, I'll probably cut up some more plastic bags to make nicer ropes.

But I'm getting ahead of myself, because, to attach a cup at the bottom, you first have to make one. Take a clean aluminum can, and cut around it. You don't have to be too precise, as long as you leave yourself enough space to clean up the edges. You just need a couple of centimeters of the "sides" of the can left, to make the bowl. (Don't tell Mudlock, but I think I made our scissors pretty dull in doing this.)

When you've got it trimmed down fairly neatly, you need to gently fold the sides in toward the center of the can. This is to prevent the birds from cutting themselves on the sharp aluminum. If you don't do this step you are a bad person and should feel bad. When you have them folded over, you can press them down with basically any rounded surface. I used a highlighter.

And you will also notice, at this point, that the "bowl" is rather convex toward your seed-spill point. This is a thing you do not want. So, take a hammer (or other heavy, blunt object) and repeatedly hit the inside of the can until it is concave, or at least fairly flat. It won't be perfect, and that's fine; just do your best.

Now you can put some holes in the bottom, in four equidistant spots. I suggest using a nail, and, as crazy and difficult as this sounds, making the holes "outward." You don't want the sharp pieces you'll inevitably end up with on the inside, where the birds might pick at them; also, you're going to run your plastic from "above" to "below," so it's more convenient for you, in the end, as well. (I hammered the nails through while the bowl rested on a roll of duct tape. That caught the nail satisfactorily. And was impossible to take a picture of while I was doing it, though I think you get the idea.)

The rest of the procedure is eyeballing and rough measuring. You want to leave enough space for the seeds to get out of the bottle into the cup, but not enough for the bottle to just empty completely. I've got about a centimeter of space; I should probably have gone for a centimeter and a half, given the bird feed I'm using. (Smaller seeds: better.)

If the photos don't seem to follow one another properly, that's because I tried a couple of different things before settling on the final design. Some of my failed ideas involved using hot glue (which doesn't stick well to curved glass, it seems) and cut-up straws, trying to attach things to the lip of the bottle (which was insufficient for the purpose), trying to attach the cup at the bottom by only two points... Yes, this design went through many stages. Two different versions of the feeder are shown in the pictures, since the first one failed dramatically after a day on my porch.

The bird feeder in use:
Before I took this out to a public place, I hung it off my porch, to see if the birds would like it. They did, very much, even with an older, less stable build. (I sound like a software person.) And they liked it even better after I fixed it up and put it in its current configuration.

Now I have hung it in a super-corporate area of town not far from where I work, so I can walk/drive by and check on it each day this week. After 16 hours, was still up, though my cell phone picture doesn't do it justice--I didn't want to look suspicious, so I snapped it kind of quickly, from a bit too far away. After 23 hours, it was still up. I couldn't tell if the birds had noticed it yet, though I'm thinking not so much.

Two weeks later, and it's still there! With a few less seeds, even!

More update: I spent an awful lot of time on this completion, thinking about what things would make good bird feeders and what wouldn't. And even after it was finished, I couldn't shake the habit. Also, I noticed that the larger birds that feed at the [gasp] store-bought feeder I've hung up to replace my hand-made one have a lot of trouble, and I have these sunflower seeds I need to get rid of... ... So, I cut up a milk carton, as you can see in the last picture. That design will want improvement, but I think it's a start.