Great idea for lego storage! Instead of flat surface, add lego mats. Creative Solutions for Small Space Play: Underbed Play Table with Drawers by Great Little Trading Co. (does not ship to U. but think of the DIY possibilities)
What an amazing idea! However, I'm sure not a day would go by before all the drawers' contents would be mixed.it would take more time to organize it everyday. The Best DIY and Decor: Playmobil Drawer Storage for keeping everything set-up.