Our son has a massive Lego collection and he keeps it sorted into different types of bricks in several PP drawer units from Muji, with printed labels on them. We do have to help him do a big tidy up every now and again but it works reasonably well. The bigger ones can take whole sets but to be honest we encourage our son to take his creations apart after a few weeks so he can build anew and they don't just gather dust. They are a bit pricey but it looks really neat and if you have a big collection it works really well.
