My requirements were easy, cheap, and it can't look like a soda bottle.
Step 1: Parts
clear plastic bottle,
plastic container slightly larger then bottle,
wire, or string, etc.,
Warning! Knives are sharp, cutting plastic can be tricky! You may need a few plastic bottles to practice on.
Step 2: Mark Top
Fill or drain the liquid (water) until it reaches the narrowing of the bottle top. Mark level with marker.
Step 3: Remove Label
Peel off the label, I used Goo Gone to remove the glue from the bottle after removing the label.
Step 4: Score the Top
Score where you marked the top. Scoring the plastic helps when it comes time to cut.
Step 5: Cut the Top Off
Cut along your scoring, save the top, we'll use it in the next step.
Step 6: Mark Holes
How you cut your holes can depend on the bird and the feed. Finch's apparently like to eat upside-down, slots are cut so they can get to the feed.
I'm not feeding finches, so I cut holes. Use the curve of the top we cut off to mark the holes for the birds to feed from. Center the top along the side of the bottle, start marking at the center top to the left then the right. As you mark along the edge you want to rotate the top, so it is flush with the side of the bottle where you are marking. Keep marking until the "curve" has "straightened out" running straight up and down the bottle. You don't want to force the top down around the curve of the bottle causing it to bend. Next to cutting this is the trickiest part. Mark a horizontal line from the bottom of the left and right legs of our curve. Now repeat on the other side of the bottle. Add more paired holes as you have room for, you'll probably want to stagger them 90 degrees as you go up the bottle to give the birds more room to feed. The intro picture illustrates the placement of the holes.
Step 7: Cut and Fold
Leaving a uncut section at the top of your marked curves, cut them out. I cut from the top down one side, then the other, then the horizontal line at the bottom. Push the section you cut in and up into the bottle. You are looking for a good tight fit on the sides and when both sides are pushed in there should be a slot to allow feed to fall through.
Cut a small X under both holes and push a chopstick through them, this will serve as the birds perch. How far below depends on bird type, the bigger the bird the more the distance needs to be.
Step 8: Lid
Score and cut the plastic cup which will be the lid to the feeder. Punch two holes across from each other in the lid, place on bottle, and punch two holes in the bottle just below the holes of the lid. Run the wire through holes.
Step 9: Drain Holes
Punch some small drain holes in the lowest part of the bottom of the bottle.
Step 10: Fill and Hang
Fill with feed and hang in appropriate location. When filling the feeder for the first time, putting it in a bag might be a good idea and help you avoid a mess. It may take a few attempts to appreciate how to cut the holes just right, avoiding feed spilling out.