If you are looking for a niche market, how's this for an idea.
On show at the recent Sign Africa show in Johannesburg were these printed bath tubs. Dr Nicholas Hellmuth, who produces the well known FLAAR reports is a regular visitor to the Sign Africa shows and he highlighted these tubs as the most interesting product at the show.
Since South Africa is home to several ink factories, one of which developed this ink for this application. One can only wonder at the durability of the ink if the tub is used every day.
Printed and then thermo formed, the tubs were an obvious eye catcher but we don't know if any were sold at the show.
FLAAR reports
http://www.large-format-printers.org