|Here's the end product. Have you seen the Baltimore Orioles|
drinking out of them on the WWN "Bird Feed" Live Cam?
You can buy reservoirs from a few local stores here in Rockport (not as easy to find elsewhere), but I have cracked several of these myself during washing, so I created a heavier duty version that would last me many seasons.
I do have a few feeders that have reservoirs that are built-in, but generally speaking the built-in reservoirs are pretty shallow, and therefore dry up quickly on extremely hot, sunny days. These are deep, so they can go several days without a refill.