The fact that they're collapsible caught my attention, but still, they're just plastic, and I thought they'd probably be unstable while actually holding water and flowers, which is the last thing you want of a large container of liquid.
I was wrong. These things are so cool! Fill one with hot water to turn into a shape-able piece and when you have it how you want it, just refill with cold water and it becomes hard again, "freezing" it into shape. When you're done, run in hot water again and you can flatten for easy storage.
What's even better is that these aren't very expensive either. They're 7 bucks (cheaper if you buy more), and would be great for your seasonal flower displays.