DIY Backpacking Cooler

Today's trail tip is inspired by this 'pin.' Have you ever finished up a long day of hiking and thought to yourself, "Gee, I could go for a cold drink and a cold bag of M&M's right now?" If you have (and you don't mind packing a little extra bulk and weight) this tip is for you. How much extra weight and space in your pack are you willing to give up for a cold drink at the end of a long day on the trail?