I have these and they are very sturdy. I have a large number of them stacked in one tall stack and because they lock together they don't come apart or tip or anything. I am going to buy more, but will get the lipless ones instead. It's a bit of a pain to get the paper out past the lip if you have the tray more than 1/3 full.
The Perfect Paper Stackable Paper Trays say it all. They are PERFECT for keeping your 12x12 pages and Layout pages in perfect condition. I am looking forward to purchasing more, whenever I get my work station fixed the way I need it. The trays make it easy to be able to get your paper in and out without tearing. Also makes a GREAT storage for your layouts in progress.