Build a pull out pantry style cabinet like this one for extra storage that takes the best advantage of the space.
This is a link to a Google 3D SketchUp drawing for a Dutch pullout table. You will need the SketchUp software to download this drawing and its freely available online. We do not provide support for this software. Not all drawings have the measurements displayed but you can use the measurement tool in SketchUp to easily and accurately determine the dimensions of each lumber part. Most drawings do not have instructions, its assumed you can build it based on the completed drawing provided.
At the link you will find three sensible solutions for disorder in your vanity.
Make this fabulous little storage unit with common cove moldings available at any home center.