We have a ton of art supplies - every variation known to man. How do you organize? Do you put everything mixed together or keep things separate? For instance, we have fat markers, thin markers, dry erase markers, color wonder markers, colored pencils, triangular colored pencils, regular crayons, fat crayons, triangular crayons, etc. I'm trying to organize but it seems like I just have a ton of little containers and then when they play they don't open different containers. Help please.