I'm not sure if this would actually be considered an invention. It's more of an idea. I got this idea a long time ago, and it comes back to me every time I eat ice cream right out of the carton. In fact, I always planned that if Illustration Friday had a topic for invention, this is what I would do:
My invention (or idea) is to have lines on the inside of the carton, so you (theoretically) know when to stop. I wonder if that would help?
I also did a drawing this way, from the point of view down inside the carton. Jerry said it didn't "read" as well, but I'm posting it anyway.