No one else has responded to this question, so I will, though I am certainly no expert on the subject. I did a search of the online Bibliography of British and Irish History, a great source for finding articles and books on a wide range of subjects. I did not find anything on Elizabethan bathtubs or toilets, however. This is probably because they did not have them, at least not anything that people today would recognize as such. "Toilets" were largely limited to chamberpots in wealthier homes, and outdoor pits in poorer homes. Chamberpots were little more than a large lidded bowl that one did one's business in, and it was then carried outdoors and emptied. In the wealthiest homes, chamberpots might be contained within a cabinet of some kind, complete with a hole in the top and a lid. Urination, especially by men, was sometimes even performed in stairwells and corners, frequently without benefit of a receptacle. Tudor houses were notoriously unsanitary. As for baththubs, bathing was a rare occurrence. It was thought to cause disease rather than prevent it. Thus there were no permanently-installed bathtubs in Tudor-era homes, not even in wealthy ones. Large copper tubs might be hauled into the bedchamber by servants (in wealthier homes) for the occassional bath, then stored "below stairs" when not in use. Otherwise, one might bathe from a large bucket or bowl. For the wider topic of Elizabethan furniture (chairs, tables, beds, etc), I would suggest looking in the art section of your library.
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