I got a bed from Walmart that looks like a little cube with a hole cut out. It is for cats, but my gang love it. My 10 lb yorkie poo loves to cuddle in there and while he is a little cramped it's his favorite hang out spot!
It was 10-12 at Walmart in the cat bed section. The one I got is a cream exterior with swirls inside. The bottom is a flat cardboard type piece, which isnt super plush, so I just made a small pillow for the interior to give it more cushion

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