Multibin Top grid markers holder

This is a gridded top that clicks directly into a Multibin shell.Each grid cell is 16.6 x 16.6mm. There's a 10 cell version (for a 2x1 bin).And there's a 25 cell version (for a 2x2 bin). I've made these to be clicked directly into the shell instead of an insert or click-rim in order to fit the Crelando felt markers you see in the pictures.Each marker is 16.55mm wide, and there just wasn't enough room for a row of 5 of them on an insert top. Obviously, they can fit other things, not just markers.What will you use them for?