Here's a cool idea.
Mara Miller, writing for Drexel U's "Table Matters," liists as her favorite household items, "all rooms inclusive," her rubber ice cube trays: one shapes the ice into spaceships, the other into replicas of Grandpa's dentures.
"Even if you have boring rhomboid trays, though, frozen liquids are a top-shelf kitchen hack," Miller says.
Among the ingredients you could and should freeze for later, rather than throw out:
Egg whites or yolks
Frozen fruit juices
Brewed coffee
See the article here.