Looking for a good idea on how to make a "cat gate"....?

Many times I have wanted the same thing to keep the dog and cats separated when they weren't getting along. I hope that you do find something but without using hardware into the walls, it may not be easy. So you remember or have seen the old wood gates the are on hinges with criss cross wood. They can be unfolded to stretch across the hallway. This would be the only remedy if you could find someone to build it. ( they look like the metal ones used in Home Depot and other stores to block off an aisle)