planchette
noun
plan·chette plan-ˈshet 
: a small triangular or heart-shaped board supported on casters at two points and a vertical pencil at a third and believed to produce automatic writing when lightly touched by the fingers
also : a similar board without a pencil
Example Sentences
Recent Examples on the Web The standout piece from the Silver Edition box is a planchette. 
Rob Wieland, Forbes, 21 Sep. 2021 Owned by Rick Schreck, a tattoo artist and the Vice President of the Talking Board Historical Society (TBHS), OuijaZilla is completely functional and outfitted with a planchette that weighs around 400 pounds. Daisy Hernandez, Popular Mechanics, 16 Oct. 2019 Ouija boards aren't foolproof and, yes, people often — whether consciously or unconsciously — move the planchette. Aliza Kelly Faragher, Allure, 19 June 2018 At first Hutchings was on the board with Curran, then others began taking a turn at the planchette. Joy Lanzendorfer, Longreads, 14 June 2018 The playful, interactive Ouija 2000 allows visitors to the site to control the planchette of a real Ouija board via remote, by moving their computer’s mouse, while watching a live feed of the board onscreen. Reena Jana, WIRED, 23 Mar. 2000
Rob Wieland, Forbes, 21 Sep. 2021 Owned by Rick Schreck, a tattoo artist and the Vice President of the Talking Board Historical Society (TBHS), OuijaZilla is completely functional and outfitted with a planchette that weighs around 400 pounds. Daisy Hernandez, Popular Mechanics, 16 Oct. 2019 Ouija boards aren't foolproof and, yes, people often — whether consciously or unconsciously — move the planchette. Aliza Kelly Faragher, Allure, 19 June 2018 At first Hutchings was on the board with Curran, then others began taking a turn at the planchette. Joy Lanzendorfer, Longreads, 14 June 2018 The playful, interactive Ouija 2000 allows visitors to the site to control the planchette of a real Ouija board via remote, by moving their computer’s mouse, while watching a live feed of the board onscreen. Reena Jana, WIRED, 23 Mar. 2000 Word History
Etymology
French, from Old French, diminutive of planche plank, from Latin planca
First Known Use
1860, in the meaning defined above