Best cat toys you've invested in?

Please post pics

Cat tree

(Not actually my cat tree but u get the idea)

Edit: i didnt generate this photo, its a link to an image that popped up. For the record, that would actually be a sick cat tree and I would buy it if it was available and I had the space for it which I do not)

A twist tie. Like the one that comes on loads of bread.

Those mf are hard to find, I keep those for me and cords