Stacking shelf

So i wanted a way to be able to stack some of my makes without having to add more shelves. I designed this ... it ain't perfect by any means, but it does have a little "divot" in the corners for the legs of another to fit perfectly to hopefully help with stability. The lip around the edge is about a half inch high. It is approx 4" deep and 4-3/4" high. I'm actually pretty proud of myself since I have absolutely NO knowledge as to what I'm doing. lol