I recovered the seat making sure the design was straight/centered. Since the seat cover will be removable, I also covered the underside securing with staples.
For the shelf, I measured the underside of the chair. I used a 3/16″ piece of scrap and cut along the 19″ lines and 17 1/8″ lines which were the measurements at the widest points. I’d cut along the yellow line which was closer to the actual size needed.
Once the piece was cut down to size, I mod podged fabric to the top side and painted the underside white.
Here’s the shelf installed with screws into the bottom corner pieces. I covered the gap you see with some cording I made using the same fabric.
I also screwed “stoppers” into the bottom of the cushion so it wouldn’t move around.
Now you can store anything you want! If you really wanted to hide something, you could even just screw the seat down for things you don’t need often. I love how it turned out and I think any kid would love it too!