Gridfinity boxes designed to hold pens / pencils on an angle

There are two variations of this model, one which is 1x3 Gridfinity units and can hold 3 pens / pencils, and one which is 2 units wide and can hold 6 of your favourite writing utensils.

The slots for the pens are 11mm which I found to large enough to hold most pens and pencils, but not Sharpies and other fatter markers.