This is a fantastic webpage inspired by Helena Dbalý's wonderful book, Playtime for Cats. The page is in German, but I used Google Translate to get the gist of the ideas! First idea: DIY multi-puzzle foraging boards, incorporating toilet paper rolls, egg cartons, bowls, and cups to inspire foraging behavior in your cat. Once you get the idea, you are only limited by your own recycling bin and creativity!
Second idea: letting your cat dig for treats in a bowl of wine corks, paper balls, wooden blocks, or other safe objects!