FLAT OUT REFRESHING: Manufacturers are forever tweaking travel aids to sell new and improved models. One product getting a particularly innovative spurt of reinvention is the collapsible drink bottle. The trick is to make a sturdy leak-proof vessel that is both more capacious and more compact than previous incarnations. Those seemingly contradictory objectives required the designers of the Hydaway Collapsible Water Bottle to think outside the, uh, bottle to create a pocket-size container that can hold 21 ounces (that’s more than 2.5 cups!) of portable hydration when expanded.