Hold Door Part Open Let Cats Pass Block Dogs Gadget

I needed a way to keep a door partly open so the cats could get through, but the dog could not. I needed this to let the cats get to the cat food and litter boxes, but I obviously didn't want the dog to be able to get to these.

This is what I came up with. It screws to the door and door frame, and will keep the door open the distance it is set for.

Print with strong filament and high infill.