Cleaning a thermos, particularly a deep one, is a real pain. UK-based industrial designer Jake Naish has designed a rather brilliant solution. Called Forss, it not only enables you to access and clean every inch of the interior without using those (largely ineffectual) bottle brushes, but also gives you the option of altering the vessel's volume at whim.

"Forss is a simple daily-use water bottle that encourages better bottle hygiene and less wastage."

"An interchangeable bottom section means the user can change the capacity of their bottle between 500ml and 750ml depending on their requirements, this feature also grants the user unrestricted access to the deepest, most contaminated areas of their bottle. The magnetic lid also conveniently clings to the bottle whilst it is removed."

"Made from insulating double-walled vacuumed steel, Forss keeps drinks hot for 12hrs, or cold for 24hrs."

Sadly Forss appears to be just a concept. It's not the first object Naish has designed that we wish was in production; also see his beautiful Magnus Chair.