My PVC dolly is a little different than some here, but works great for me. I made it modular so I can add or remove pieces as needed, and small enough to fit in a car. (5 foot sections. Mine is more 'railroad track' style. I didn't take any pictures of my dolly, but it uses skate wheels, offset from each other, on a piece of angle iron.
One section:
Sections are butted up next to each other, then filed to be flat. I marked each section so I know what connects to each.
Notched the 2x4 for a little more stability. Counter sank the screws.
I screw in the screws on each 2x4 till the pipe is slightly oval. You'll have to play with your dolly a bit to get a smooth roll. You might need to adjust the screw.
Right now I have 20' of track, and can put it together in less than 3 minutes.