This Genius Ikea Hack Adds Loads of Storage

Build mini cages on the sides. This is so you have something to secure the drywall to. We recessed the drywall on the sides but in hindsight I wish we hadn't. You can suit yourself, but just check the depth of these cages. When it's all said and done, you'll have dry wall on top of them and then trim on top of that, so make sure they aren't protruding too far.

Use screws to attach the side cages to the top and bottom cages and the outside walls.