Melt chocolate/candy melts in the microwave in 30 second intervals until nearly completely melted, stirring between each turn. Once there are only a few lumps left, allow to rest in the microwave for 5 minutes to allow the heat to penetrate and melt them. Be careful to not burn the chocolate/candy melts.
Pull a spatula along the side of your bowl to be sure there are no small lumps remaining. These will create a grainy final product.
Change your bowl - scrape all melted chocolate/candy melts into a fresh bowl.
Warm corn syrup in the microwave until just barely warm.
Add the warmed corn syrup to the melted chocolate/candy melts and gently, slowly pull the corn syrup through the mixture. Be sure to scrape all chocolate/candy melts from the bottom and allow the corn syrup to make contact with all of it.
This shouldn't take more than about 30 strokes of the spatula, and it's important to stop as soon as the mixture looks like softserve ice cream or ricotta cheese.
Once you’ve finished mixing, pour your mixture out onto a piece of plastic wrap, flatten in with your spatula a bit, and wrap it air tight. Leave it to sit on your work surface to cool and begin to firm up a bit. If you lay your plastic out over a baking sheet and wrap it there, you’ll be able to move it from your work surface with ease.
Candy clay sets a bit quicker than modeling chocolate. Once cool and set, but not firm, unwrap and work the modeling chocolate/candy clay through your fingers to smoosh any tiny lumps that may have formed. Then gently knead all together.
Use it now, or wrap it airtight in plastic and store it in a large zipper bag or airtight container. You can freeze this if you want to keep it longer than a few weeks.