My son used Grandma’s aluminum colander with a wooden pestle to make apple butter for the fair. It’s a tool you don’t see very often in the kitchens of people my age, but your grandma probably has one. They can be used to make everything from jelly to cottage cheese. You can find many apple butter recipes online, but if yours doesn't involve putting cooked apples through a sieve, don’t expect a blue ribbon.
If you’re looking for a "modern" way to use a colander and pestle, you can make your own almond milk using this recipe.