I recently started using 12x12 page protectors for all of my stickers and masks. A package of Thickers fits perfectly with the two sheets side by side. I put a piece of cardstock in for stability, and put a package on each side. All the other brands are in here as well. For the smaller masks - like the 6x6 Crafters Workshop ones - I got page protectors that are divided into sections. The divided ones come in all sorts of configurations if you want to organize more specifically.