I also made a door prop. out of an old metal door.
and got some block donated so they could cut through concrete
Agreed, you can't beat the real thing. However, buildings aren't always available so we built a roof simulator with the ability to change the pitch to a 12/12. The size of the work platform is about 20' by 16' and we have two framed out areas so we can drop-in pre-made panels of sheating with roofing felt and shingles. This way we reduce the down time to replace the roofing materials. A few drywall screws hold in the panels and after the cuts are made, pull the screws and drop in a new panel. The prop is large enough that we can also train on cutting from the bucket (tower ladder bucket). This had turned out to be an excellent training prop.