Fun with shadow puppets! You can do these with kids of all ages. I did them with two and three year olds. While the cognitive ability to figure out the idea of the shadow, etc, was very different, everyone still had fun doing them.
DIY top loading cat litter boxes plastic storage containers with lids feet of grey stair-tread carpet -carpet adhesive double stick tape. I like this idea, but i don't think my older cat would be able to jump out