Perusing the global buckets webpage, I saw an idea to make one out of 1 bucket and the top from a 5 gallon water bottle. So I had to to try one.
Take an ordinary water bucket-cut the top, drill a bunch of holes, put a rage over the pour spout, make sure to drill or cut a hole for a 1" or larger piece of tubing to go into - this is how you are going to add water to your planter!
Shove it in the 5 gallon bucket- pour side to the bottom
Fill with water up to the pour spout, fill with dirt and plant! I put a cayenne pepper in this one- now it goes into the green house for warmth!
Note- You may want to add a few "overflow" holes in the bucket... just put them beneath the level of the water bucket top (where you cut it off), and above the spout! Save the bottom of the water bottle for a bucket, or re-use as a planter!