Top of Frame Door Cracker

Never lock your cat in (or out) of your room again! Simply place this doorstop on the top of your doorframe, with the "P" facing towards the frame. Slide to the left-or-right to change how far open the door remains. You can put some rubber or softer plastic on the curve of the P to create a softer contact-surface with the frame.

This is the first version of the Doorstop, and looks kind of ugly. I will be making more iterations in the future.