These interlocking modules are available in 1" and 3" heights (+1/8" for the top), are infinitely stackable, and have custom-sized racks for Sharpies (13mm diameter, 24 slots), Uni Posca Small pens (15mm diameter, 18 slots), or Uni Posca Medium pens and fat Sharpies (17.5mm diameter, 15 slots).
The modules are designed for 1/8" medium draftboard, and the friction-fit pieces can be assembled without glue. To assemble, choose a base (with or without side panel slots), the sides (1U or 3U height), and the appropriate rack.
Assemble all parts with two tabs down, one tab up. To add a new module, assemble it minus the base, then slot the exposed tabs into the top of the first module. Mix and match as you like!
I came to the forum looking for kerf gauges so I can make a box specifically for my pens. Thank you. You’ve made my life easier. it’s been a rough week, so thank you again.