I just use fencing. I cut the fence so that there are long pieces of fence that can be wrapped around the "door" section to swing open and close. I then latch the door with a carabiner. I can take a pic when I get home. It will probably "explain" things better.
Inside of a building, I once divided off a section with old pallets. I think I tied them together with string, and untied one part to use as a door. The top might have been a solid piece of plywood, so chickens on top couldn't poop on the ones inside.
It was a temporary setup, but it worked well enough for as long as I needed it.
Dog kennel panels can also make good dividers. Baby chicks and small predators can go through them, but if you use them for adult chickens inside another enclosure they are fine. (But they can be expensive if you buy them new, so getting them second-hand is a good idea when possible.)
Hope these help. I circled where I bent back and twisted the fencing to make a "hinge". I twisted the pieces of fence around and it makes it easy to open and close.
This last pic shows the carabiner and I also bent back the long pieces of the fence so that there wasn't anything to poke my birds. The other end of the fence is attached to the end of the run so that it divides the run down the middle - I bent the pieces on that end to hook to the wire that's set up for the run.
Here's a pic of the run, I use the temp fence posts to keep it steady.
I have also set up temporary areas with the fencing and or a larger dog pen for integrating.