1896 Folding Toilet Cabinet, Marshall, MI

I am asking for help in valuating this rare piece of antique furniture manufactured by the Folding Bath Tub Company, Marshall, Michigan, patented July 14, 1896. According to a manufactures advertisement it is called a Folding Toilet Cabinet with brass spigot and copper top and wash basin.

I have searched for years for information on this piece and have even engaged several appraisers but know one has ever seen one before. I have owned this for 50 years and to the best of my knowledge it is complete and in very good condition – more information available if needed. Can anyone help me with establishing a fair value for this piece? Any information or help you can provide is gratefully appreciated.