I had built a number of oak shelves for my man-cave, and a decade later they were no longer suiting me. So I took them down. What to do with a bunch of oak shelves? I re-purposed them as drawer inserts for my tool chests. Various arrangements accommodated the different heights and configurations I needed.
The basic construction principle was to hold the plank in the mill, and cut so as to leave about 1/8″ at the bottom. Using a ball end-mill on the divider edges and the more-narrow slots, reduces the stress (compared to square edges and corners.