Simple Door Stopper/Ajar

Story Time:
I have a cat, and keep her litter box in the basement. To get to my basement there is a door. Normally it's not a problem, the door is kept open all the time, and if it gets closed lightly and not fully, the cat can usually open it my pawing at it. Now recently I got a second cat in my house for a little while and they don't really like each other, but somewhat seem to tolerate each others presence. One day, I wake up, the door was completely shut and my cat left a small present on the floor. I blamed the girlfriend, cleaned it up and went on.The same day, while watching TV, I see what is actually happening: new cat goes into the basement, old cat sees this. She hops off her spot and runs to the door, and she closes it... Then she hops onto it to make sure it jams properly, locking the new cat in the basement but also losing access to the litterbox! So now I had to say sorry to my GF, and after not finding anything simple on thingiverse I quickly made this thing up and pri