The circle CCRs were built by a fellow named Dennis Cherry. Below is from an email from him:

If making these out of PVC, you will need to do cross bracing to keep the PVC from sagging and not have a nice circle.

The total length of the circle is 196 1/2". To make the ends of the CCR to join, I used 196" to have the ends over lap so the first and last pixel spacing was the same as all other LED's in the string.

I would suggest using the 1/2" or 3/4" gray electrical PVC, this has slightly more flex to make turns. The white PVC is not maded for tight turns.

The circles can be held in place buy using 1/2" or larger re-bar, I used 5 foot length, 2 per circle spaced 63" apart.

To attach the circles to the stakes, I just used hose clamps 1 per stake.

I used two string lines to keep everything straight and level. One string line on the ground for the stakes placement in a line, the other string line is for the clamping height of the circles and goes between the first and last rebar stake.

Stake placement is:
s-------ss-------ss-------ss-------s

You will need 2 stakes next to each other as shown.

Picture:
(Click on a picture to view it full size)

Full View of the Circles

Close up of circle clamps

Close up of zip ties