Lays flat to travel
Perfectly fits ink sample bottles (Goulet’s, too). The tray is sent in a flat bag... like an IKEA furniture. So you slide the parts together. Takes 2 minutes, or 5 if you are blind, have only one hand, and waist deep in lava.
Note, the plastic is quite brittle. I broke a wee piece off the rail of one tray. It had no effect on the function. I think I did pretty well, being waist deep in lava.