If you have a sink in your bathroom, it would be a wise decision to build a practical cabinet underneath it. A wooden cabinet like this can perfectly cover the lower part of your sink and therefore a potential bad smell can be prevented. Additionally a such cabinet can also be used as a storage space where you place some bathroom products.
You can also attach a toilet paper roll holder to this cabinet. The sample seen in the picture is a black color wooden cabinet built underneath a sink with a toilet papaer roll holder attached to it.
Photo via: diymamas.blogspot.com