This is so much fun for kids! I used to do it in my classroom and we’d use snow in place of the ice in the winter.
1 cup heavy cream
1 cup milk
1/3 to 1/2 cup sugar
1 tsp vanilla
(For chocolate ice cream, cut the vanilla in half and add in 4 T. cocoa)
1 lb. coffee can with lid (or something similar)
3 lb. coffee can with lid
1 cup rock salt
about 6 cups ice (or snow) (more if needed to fill the can)
Mix all ingredients together and place in the smaller coffee can. Seal. (If I think the lid is a bit “iffy”, I will duct tape around it to add extra security). Place the small can inside the larger one. Pour the rock salt and the ice into the larger can so that it surrounds the smaller can. The fun part of doing this in these cans is that the kids can take turns pushing and rolling the can around to mimic the action of an ice cream maker. It takes about 20-30 minutes to get it to the proper ice cream consistency.
You can also do this with Ziploc bags but I found that they didn’t work very well in a large group of 4 year olds as the bags tended to puncture. With a smaller group of children or older children, this method is fine though. You put the ice cream mixture into a smaller sized bag, seal it, and then put that into a larger bag for the ice and salt. Instead of rolling it around like with the cans, the kids will need to wear gloves so that they can squish the bag until it’s mixed and the proper consistency. Fun!