This is going to be so great!
The design is simple- two arches with three braces to stand them up; The legs are capped with PVC caps (to hold the water in). Each of the legs and the top is made of two 2 1/2 foot sections joined with a T-shaped joint; the braces are five feet long (uncut). We used 3/4 inch PVC, although other blogs used 1/2 inch. For inspiration, a more decorative version is here, while a simpler version is here.
We opted not to glue the joints. I agreed with the ideas in this blog, where she says that the pieces hold together well without glue, and no glue makes it easier to (purposefully) take the thing apart to store it.
The magic of this is that Mr. Unwired used a 1/16th inch drill bit to put holes (11 in total) into the PVC structure, so that when the hose is connected and turned on just a teeny tiny bit, it sprays water... like this:
The blog linked above referred to putting misters in the holes. That would be awesome, but I haven't been able to find them. The guys at my local hardware store said that I should look in the sprinkler supply section of a garden center. Sounds like a worthy addition to the fun!
Without the misters, I looked high and low for something we already had on hand that could be added to the cooler. Yes, you guessed it... those are paint rollers! These rollers came our way when a friend moved to NJ seven years ago, so it seemed like a good bet to string these on one end of the cooler to bump and splash the kids. Worked like a charm, for no extra $$$!