Building the rabbit tractor took a lot longer than I expected...somewhere close to 8 hours altogether I think. We had to do a lot of figuring with the cattle panels to come up with a height that is both roomy and sturdy - 16' was too wobbly and would have required supports.
The frame is 4' wide by 12' long and we used 3 cattle panels which are 50" each. That gave us a little bit of an overhang out the back which I'm hoping will keep the nest area a little less drafty.
I wanted a nest area off the ground so they could have options in our hot summers. They can go into their nest box, or lounge on the plywood, or go under the plywood where the tarp doesn't reach so it's shady but has better airflow.
We also laid down 2x4 wire on the bottom to discourage digging. Hopefully we don't also discourage nibbling but the spaces are large enough I think it will be OK.
All in all, I like the design but next time I want to try with PVC pipe and chicken wire. This thing is too heavy!