At least 30 feet of pvc, 1/2" or thicker
About (10) 1/2" T-Connectors
One 8'x10' tarp or larger
PVC cutter or a hacksaw or sawsall for cutting pvc. Note, a pvc cutter is cheap an will make everything go much faster, plus they are a cool tool to own.
Clamps of bungies to secure tarp to frame (duct tape would also probably work, or just having a very big tarp)
Final pool size is ~ 4x6 feet
If you have an old queen sized inflatable mattress that doesn't hold air very well, you could probably cut that open and use that instead of the tarp
WARNING: NEVER LEAVE YOUR CHILD UNATTENDED IN THE POOL! A CHILD CAN DROWN IN LESS THAN AN INCH OF WATER.
WE ARE NOT RESPONSIBLE FOR ANYTHING YOU DO.
Step 1: Collect your stuff, line up the PVC
You will also need a bunch of t-connectors. You can buy packs of 10 t-connectors from Home Depot or a similar store for a few bucks.
I used 16'x10' foot tarp folded in half the long way (so it was 8x10). You want a relatively new tarp so there aren't any leaks in it. The tarp will still let seep water through but it seems to hold it well enough to play in for a few hours.
Plan to make your pool about 2-3 feet smaller than the width/height of your tarp, this gives you an extra foot of tarp on each side for attaching the tarp to the frame.
Example: For and 8x10 foot tarp, make a 6x8' frame (actually you might want to go about a foot small than this -- I did a 4x6 frame and that worked pretty well
For this project I'll assume you are making a 4x6' frame
Note that the sizing here is approximate. Your goal is to have the long sides have a split in the middle for a supporting leg, and the short sides to have a long section and then a short section connecting the side leg to the corner (see later steps to clarify this)
All of this is approximate, with some extra connectors and a pvc cutter, you can just shorten things or lengthen them by connecting two pieces as needed.
[NOTE, PVC is a terrible building product for the environment, so this is a better project for using up unused scrap pvc rather than buying it new...]
Green Building council report on PVC:
Article - http://www.inhabitat.com/2007/03/26/pvc-no-good/
Report (PDF) - https://www.usgbc.org/ShowFile.aspx?DocumentID=2379
PVC pipe summary is on page 9 of the pdf; General summary of impacts is on page 11]