Tim Hunkin’s website – http://hunkinsexperiments.com/ – Hunkin’s Experiments is full of wonderful ideas, here are a couple to try out:-
(The book is now sold out, but you may be able to get one second-hand).
Visitors to Cabaret in Covent Garden were often entertained by Tim Hunkin’s Oracle. A lovely lady who answered your questions with a Yes, No or a ?. It was quite terrifying as the stencil disc spun in the air like a circular saw, while you waited with a licked hand ready to receive the answer which was written in sand – poured through the stencil. The sand got everywhere and ruined the coin counting machines!