We mainly use plastic tubs in our Expedit shelf unit but I have found the key is to rotate rotate rotate. I regularly go through everything and then cull - send to op shops and keep out about 4-5 main things they like, puzzles, dolls, strollers and a few other bits and that is it. Blocks, train tracks, cars are all on rotation and come out for a week or so then back again. I have been amazed at how little they actually need out but it has been a godsend for me because the mess does my head in.