Icecube tray floodwall

I thought of this while reading another idea, and I think it's better in a lot of ways. The idea uses the same concept as icecube trays, only on a gigantic scale. Huge, heavy-gage metal icecube trays, which would be stacked in large warehouses until needed, then laid in place via forklift or helicopter. Basically, lay one layer, fill it with sand, water... whatever's handy and heavy, then lay another layer on top of it, and repeat. Should only take a few layers to get a pretty high wall. Each tray has a rubber seal atop it and on the sides to form a watertight seal with the adjacent units, and they lock together with huge steel pins to keep the water from pushing the layers apart.

This is the fastest, strongest, and least labor-intensive method I can think of to hold back floodwaters. What do you think, guys?