I did find the following directions for making the PVC floor frame:
http://www.ehow.com/how_4928734_make...ing-frame.html
Just be sure to read all the comments first (one said there is a cutting mistake in the directions), and make sure you can get the correct size snap clamps when you purchase the PVC. It's just me, but if I were going to make one of these, I would definitely go to a place that would cut the pieces to correct lengths for me.