This was the first thing I ever designed in fusion 360, so when I say simple, I mean simple… but it worked for what I wanted so I might as well share it. It doesn't have a locking mechanism like the original so not suitable where safety is a concern, but it allows the gate to open only one way which is fine for keeping my dog where he needs to be.

UPDATED: spent some time refining the design and tidying it up abit, still functions the same.