Green’s Dictionary of Slang

any nameless small object, typically some form of gadget.

1911		DN III 543: Doodinkus.
1914		J.C. Ruppenthal ‘A Word-List From Kansas’ in DN IV:ii 105: dinkus, n. Thing; jigger. Also dodinkus, dudinkus. ‘This little dudinkus belongs to an automobile.’.
1945		in L. Perkins Flight into Yesterday 182: The whole doodinkus is suspended from the roof or ceiling so as to hang a few inches above the floor line.