Told my kids that they could have $150 to build a tractor that was predator proof, whatever they didn't spend they could keep evenly split between them.
Got PVC pipe and roof rafters off CL for free. Bought some heavy duty hardware cloth. Had some scrap wood around they used. Erm, they found wheels, not sure where exactly but it was legal.
I did no work at all and had 3 meatie tractors in 2 days. They are similar to the Salatin except they have the roof rafters for a top instead of a flat top, the wood goes over part of it for shade, then wire fully surrounds the entire pen. The ends open to grab birds. Plus the best part we found is the heat rises away from the meaties, so they are more comfortable.
3 tractors, they spent $60. They were happy.
But proof the kids are chicken fans? The reason they built 3 tractors, they went out and bought more meaties with the money.