melt chocolate in a microwave safe bowl 1 minute. Stir. If not fully melted return to microwave for 30 seconds at a time, stirring after each addition. Do not get the chocolate too hot. Can use a double boiler to melt the chocolate. Just have the water only to a simmer.
When the chocolate is fully melted. add the Karo syrup and stir to blend. The chocolate will come together and appear dry and crumbly.
Pour the mixture on a piece of wax paper and flatten into a disk. Cover with another piece of wax paper. Then leave it alone for at least 8 hours.
After setting for 8 hours remove the wax paper and knead the clay candy. It may get too soft to handle if you touch it too much, if so set in the refrigerator for a few minutes. Add powdered sugar or cornstarch if it gets too soft and sticky. Add only a little at a time. Have fun