I have had these trays for probably ten years. I knew it would come to me.
There was a reason I moved you shelf to shelf, and studio to studio.
So I clamped them together 4 at a time and drilled holes, using a tray from the last batch as a guide, so all of the holes would be the same.
Painted some of them with chalkboard paint and eyeballed the spacing (then I checked with a level)
walla! now it is a collage wall, I am using some for scrap booking pages and some for ideas. Perfect for my nursery sized studio.