Helen Duncan

 

From Wiki - a Scottish medium best known as the last person to be imprisoned under the Witchcraft Act 1735 for fraudulent claims. She was famous for producing ectoplasm which was proven to be made from cheesecloth.

https://en.wikipedia.org/wiki/Helen_Duncan

In 1926 she developed from clairvoyant to physical medium by offering séances in which she claimed to be able to permit the spirits of recently deceased persons to materialise, by emitting ectoplasm from her mouth.

In 1928, the photographer Harvey Metcalfe attended a series of séances at the house of Duncan. During a séance he took various flash photographs of Duncan and her alleged "materialization" spirits including her spirit guide "Peggy" The photographs that were taken reveal the spirits to be fraudulently produced, such as a doll made from a painted papier-mâché mask draped in an old sheet.

https://www.curiousarchive.com/helen-duncan-ectoplasm-medium-britains-last-witch/

The Bangs Sisters

From the Kinja archive:

Found this in the Paranormal Hoaxes section of the Forteana - Wiki Wormhole. They produced spirit paintings. Very successful con in Chicago in the 1870s-80s. A few careful skeptics finally exposed them.

https://en.wikipedia.org/wiki/Bangs_Sisters

Magician Milbourne Christopher has written:

Wilmar (William Marriott) had read about the marvelous paintings produced during seances by a pair of Chicago psychics, the Bangs sisters. He wrote David P. Abbott, an amateur magician and investigator of alleged psychic phenomena, who lived in Omaha, Nebraska, asking if by chance he had solved the mystery. Abbott replied that not only had he duplicated the marvel, he also had added several touches to make the feat effective onstage. Abbott described the routine in detail.