I never thought of ping pong balls!. my cat has a collection of unbreakable xmas ornaments that he plays with. which of course, i found after taking care of all the xmas goodies and they were under all the large furniture. it was too much of a bother to take care of the ornaments so he has extra toys. and yes, last night, at about 9pm, little boy gets in the carrier and comes back out, meows, gets back in the carrier. broke my heart, i didn't take him out for his ride. should've thought about it before it was my bed time. my kitty came with a taj-mahal of cat carriers. i think maybe its more for a dog than cat. my mom's cat carriers are much smaller than mine. she did get a larger carrier finally for her 25# boy, more like mine. all you saw of her boy in the cat carrier was all the fur sticking out of the air holes and his head by the door, he could hardly move in that thing.