This is a stackable marker storage. I didn't just want to design something that was a block with some holes in it because I didn't want the markers to be on either end. markers being on end have a tendency to either dry out prematurely or leak inside the caps. Laying horizontal gives the marker a better longevity.

Colored caps stick out for choosing the right marker

The risers are designed in such a way they self center so there are not sliding around.

12mm markers @ 100%. (assuming you can scale for your marker)

UPDATE.

Added the newest file. the system works great and going to remove the previous versions as they had their issues.