My dog broke the end stop on the sliding window of the screen door of my RV. Rather than buying the sliding part and the end stop, I designed one in Sketchup and replaced it.

This seals off the window where you reach through the screen door and access the door latch.

It mounts with two screws into the screen door frame.

Some versions use two more screws in the face of the frame. If yours needs the additional two screws, drill the holes to match the holes in the screen door frame.