Place chocolate in a medium heat-proof bowl set over a saucepan of simmering water. Melt to 110 degrees.to 115 degrees.
Place light corn syrup in small heavy-bottomed saucepan; heat to 95 degrees. and pour into melted chocolate. Add cocoa butter; stir well to combine. Set mixture aside in a cool, dry place, stirring occasionally until firm and pliable, 1 1/2 to 2 hours.
Wrap mixture tightly in plastic wrap. Shape into a flat disk, and chill until firm, about 1 hour. Transfer mixture to a clean work surface; knead to a smooth consistency. If modeling chocolate is sticky, sift a light layer of cocoa powder over work surface prior to rolling out. Store wrapped tightly in plastic wrap for up to 1 month.