The effect of causing a ring or paper clip to move magically up a series of strands stretched between the fingers of both hands was devised by Tom Sellers: “A Ring Moves Up—and Down” in Top Twenty, 1958. n.p. Sellers used a ring tied onto a loop of string made with three strands.
Dan Harlan updated the effect, using two rubber bands and a paper clip: “Up and Down the Ladder” in The Linking Ring, Vol. 66 No. 12, Dec. 1986, p. 75. Sellers’s method and Harlan’s are notably different.