Note: To prevent the corn syrup from sticking to the measuring cup or spoons, spray with Pam or grease with vegetable oil before measuring.
Melt the chocolate in a double boiler or metal bowl set over a pan of simmering water. Stir the chocolate until melted and smooth. Remove from heat and stir until smooth and cooled a bit.
Stir in the corn syrup. The chocolate will stiffen almost immediately. Stir until completely combined. Transfer the chocolate to a sturdy plastic freezer bag and refrigerate until firm (about 2 hours).
When the dough is firm, remove from the refrigerator, and knead it until it is soft enough to work with. If it is too hard, cut off small pieces and knead until pliable. Grease the counter where you are working with oil or spray with Pam so the chocolate won't stick.
At this point you can make the chocolate into whatever shape you want. Some ideas: It can be formed into a long rope or braid and wrapped around the base of a cake. It can also be placed around the outside top edge of the cake.
This dough can also be used to make ribbons to cover a cake. To do this pat your dough into a disk shape and roll dough out to desired thickness using a rolling pin or else use a manual pasta machine. This dough can also be used to make flowers, leaves or any other decorations.
Well wrapped it will keep for months. If it gets hard to work with, knead in a little more corn syrup until it is pliable again.