How to build a multipurpose raised bed protective cover

I will cover the entire frame with plastic when the first frost warning for our area is announced.  Also, if you have veggies that need protection from the sun,  put some shade cloth over the frame.  I only made my frame 2′ tall, but if you need it to be taller, since it is PVC, this should not be a problem.  Some couplings and extra PVC should do the trick.