There are some days as a stay-at-home mom where I wake up and wonder how I'm gonna entertain the kids for the entire day. At 40+ weeks pregnant, that is my dilemma pretty much every day.
Enter our dashing UPS guy, who delivered a large box with a lot of bubble wrap (and a breast pump, but I didn't let the kids play with that). The kids spent the first part of the day playing with the bubble wrap. They popped it with their fingers, and then put it on the ground and stomped on it, and then wrapped themselves in it, and then cut it into small pieces. It absorbed their attention for hours.
(And yes, they were closely supervised as they covered themselves in plastic.)
Once they bored of that, they turned their sights to the box. They used it as a fort, then it was a spaceship. They read books while sitting inside. Then they started taking turns wearing it and pretending to be a monster.
They played contently until naptime. AAAAAAHHHHHH. I needed that today.