Lenticular Printing
Lenticular printing is a technology in which a small, ribbed, plastic lens is used to produce images with an illusion of depth, or the ability to change or move as the image is viewed from different angles.
Lenticular printing was introduced to The Hobby in 1968 by Topps with an experimental 12-card 3-D set. Throughout the 1970s and 80s, Kellogg's produced a series of "3D" baseball cards using the technique.
In 1986, Optigraphics, a Texas-based printing company that had produced Kellogg's 3D cards, received an MLB/MLBPA license of their own and produced 1986 Sportflics -- the first traditional baseball card set using lenticular printing.