I've finally made my first batch of modeling chocolate using Wilton candy melts and the finished product was not smooth, in fact it was pretty gritty. Here's the first run.
Here was my process:
1. Melt 10 oz candy melts in the microwave and stirred until smooth, no lumps.
2. Warmed 1/3 cup corn syrup for about 30 seconds until just warm.
3. Gently stirred together until incorporated.
4. Poured out onto plastic wrap and let cool about 2 hours.
5. Kneaded for a bit until soft and workable.
**as it set up, it did seem pretty oily, but that coagulated as it set.
In my experience, just let it rest longer, until it's chilled all the way through, then keep kneading til the gritty texture is gone.
If it gets sticky, put it back in the fridge to firm up, and then keep kneading. It should go away eventually.
My recipe calls for 16 oz of chocolate per 1/3 cup syrup.