Build Super Strong Shelves
Simple Edging. Although it adds a small amount of strength, the main purpose of a strip of thin edging is to cover up the plywood edges.
Wide Hardwood Strip. To add strength, but still maintain a “thin” edge, use a tongue and groove joint to add a wide hardwood strip to the shelf.
Turn it on Edge. Taking a wide hardwood strip and turning it on edge (top photo) significantly strengthens the shelf without requiring a lot of additional work. Adding a tongue and groove joint (bottom photo) adds just as much strength, but the joinery makes aligning the edging and shelf a snap.