Hubby helped me design it and we specifically made it with multiple sections so we could have multiple sizes. I figured 2 - 3 snap clamps per section, but I actually purchased 30 because I wanted extra and I didn't want to pay shipping again to reorder. The best price I found online was at littlegreenhouse.com. The clamps are 4" but you can also buy 4 foot pieces.
The pipe is 1/2 inch. We debated about using 3/4 inch but the 1/2 pipe is sturdy enough with it cut in smaller pieces. There's 4 1/2 yards of flannel at 2.97/yd - Walmart. My costs including acetone (Walmart) to clean the pipe and colored plastic tape (Walmart) to mark the sections was $71.00. I still need to find a bag - looking at military surplus duffle bags for that. I could make something, but I just don't want to. :-)