Microscope Slide Holder for Microtomy

Stackable tray to hold microscope slides on their long edge.  My intended purpose was to be able to hold/store slides that have pre-cut tissue controls for easy access during microtomy.

There is an area at the front for a label to identify the type of control being held in the tray.  

This version can hold 29 slides.  Why 29?  I needed something quickly and wanted to ensure that it would fit the print bed.  Happy to revisit if people need a multiple of 5 - say, 25 or 30.

Plans to add a raised number series along one edge and maybe a separate model with a double row (so, 2x30 positions?)