With the original make the box wouldn't close for me on it's own because the box was creating friction with the tail and the cat's nose was getting stuck on the box.

Only the box changed so if you printed the original version you only have to print box3.stl and boxmechanic.stl.

Also a rework of

https://www.thingiverse.com/thing:5938513

You can use two M3 bolts to mount the box mechanic.
I used two M3x8 screws and at the start used some pliers to get them in. After they get a grip you can tighten them with your fingers or continue with the pliers.