I love it when that kind of thing works out! Kind of like how 1/2" Tubing fits perfectly into 1/2" pvc (the thicker walled kind). Or how the 1/2" pvc fits right into the 3/4" pvc. I've made a few diy couplers lolThe fact that the shelf and the metal grate are exactly the same size is mere coincidence. Lol.