Plastic protector corners the market on drawer slides
I needed drawer glides for a cabinet I was making, and all the stores were closed. Digging through my scrap pile, I stumbled across a length of clear-plastic outside-corner molding (the kind used to prevent damage to paint and wallpaper in the house). I glued the molding to the drawer sides, and it proved a great low-friction surface for the drawer operation. If you don't want the molding to show, you could glue it into the corner of the case instead, as shown in the drawing at top.
—Charles Szuch, Calgary, Alberta