Hard to make a waterer that's as secure as store-boughten ones. However if you don't mind some spills/floods, take a bucket. Find a pan (like an oil change pan or some such) a couple few inches wider than the bucket. Measure how deep the pan is (this is important!). Now drill several 1/2" holes around the top edge of the bucket, with their distance from the bucket rim being about 3/4" less than your measurement of pan depth. (This avoids overflowing.)
To use, fill bucket with water. Put pan on top. Holding pan against bucket, flip the whole assembly over real quick so not too much water spills. Presto, you now have a vacuum-style waterer... until some chicken bumps against it and tips the bucket over and all the water comes out *plooosh!*
If you want to join the bucket and pan together, one thing I tried that actually seems to have worked for two days so far is this:
I used a screw gun to quickly screw the two pieces together, then I dripped wax on the bottom side around the screw to create a seal. My waterer is a half gallon jug and a tupperware though. It might be harder to get through one of those pans and a thick plastic bucket. Also, now that I'm thinking about it I might have to throw the whole thing out if the screw rusts. Oh well, only took me ten minutes anyway!