These cat window shelves are Ikea hacks, just regular shelves with a nice soft bed on top. Would be a good idea to put Velcro between the bed and the shelf to help keep it in place. And never mind the link, it doesn't lead anywhere of relevance.
At first it was an old end table and then they painted it and then sprayed clear spray paint on it then you turn it upside down and put a pillow in voila it's a dog bed. do this with a coffee table also for big dogs