I made this bird feeder because I didn't want to drill any holes into the building where I live, so this just plops in place in the window sill and is good to go. It will work in any modern window.
Step 1: Gather Needed Items
1-Frame--I used an old screen print frame, but I bet any old frame would work.
2-Mesh or Screen--for bottom of tray, something permeable, but that seed won't fall through
3-1/2" or 3/4" piece of wood the same length of the longest side of the frame you chose
4-L-shaped fastener with screws
5-Long nails or Screws, a hammer, and a drill if you have one
Screw the L-shaped fastener onto the wood plank as pictured, so that it will latch over the lip of the window sill. Screw another one to the other side of the wood plank.