Small Floating Shelf

My mom wanted a little shelf for her tablet over the treadmill so I threw this together. The shelf itself is actually a small bamboo cutting board from the dollar store that friction fits into the shelf frame. Then two arms are inserted from the back into the frame and held via friction (may need to lightly hammer them in as I made the fit permanent). As for installing into the wall, I used a drywall anchor kit from lowes but probably just about anything will work. Not sure what the max weight t