Blackberry Coconut Milk Ice Cream in a Bag!

How did I not know you could make ice cream in a bag? I have no idea, but it was delicious! I was not sure how it would work out being vegan and using coconut milk instead of cream, but we thought we'd give it a go.
 

Armed with two sandwich bags filled with a tablespoon each of sugar, we went out and picked some fresh, juicy blackberries from our yard. We threw them in with the sugar and Kaia happily smooshed them all together.
 

 To that we added a teaspoon of vanilla and half a can of coconut milk to each bag, and Kaia smooshed those all together, too. We put each mixture into a large bag half filled with ice and perhaps a 1/3 Cup of salt, and Kaia shook, danced, and jumped with it for several minutes. After that, she proclaimed it too cold, and I shook the bag for a few more minutes.
 

We rinsed the salt off the bags and opened them up. Oh, what pretty ice cream, and oh! Was it good! We ate one bag and put the other in the freezer for another day. I wonder how you could do this without using plastic bags? I think the mixture at least could go in a glass jar, but I'm at a loss when it comes to the ice. If anyone knows, please share! Kaia wants to make more (of course!) and I would rather not do it in plastic.