One of our summer fun activities was to do ice painting. To make the ice paint, I put a few drops of food coloring into the water in an ice tray. Then I put it in the freezer for a few hours until I had colored ice.
Once the ice cubes were frozen, I popped them out of the tray and put them in a bowl so the small people could begin painting. It was fun to use a new art "medium". The only complaints - 1) the food coloring stained fingertips (it washed off later that day) and 2) there were some chilly fingers after a while.