I've now improved the design.
I realized that all I really need to do is MODIFY the bottle threads to fit a hose.
Soda bottle plastic is formed by heat and blow-molding, so it figured that if I just added a little heat, I should be able to soften the plastic, and then use the threads on the hose as a mold to make the bottle fit perfect.
Sure enough, with just a little heat, the threads matched up perfect! Poke a few holes in the bottle, and turn on the water for some low-tech, recycled, backyard summer fun!
Full directions on my blog:
http://ecoprojecteer.net/2012/07/sod...-even-simpler/