But of course it looks better with chocolate in it:
Chocolate is typically conched for 2-3 days at a temperature between 140 - 167 degrees, depending on the company's process. ETA: oops, forgot to note that this is the step where the other ingredients are added to make the final chocolate product: emulsifiers, sweeteners, milk products for milk chocolate, etc. It isn't just pure chocolate that gets conched.
After conching, the chocolate must be tempered in order to work with it properly. Tempering refers to bringing chocolate to a certain temperature in order to stabilize the crystals. From conching, you'd need to cool it down to 104 degrees. If you're starting with solid chocolate bought from retail, you'd need to melt it first, get it to the proper temperature then cool it down to its working temperature. Dark chocolate has a higher working temperature than milk and milk higher than white. When I was in culinary school, we would melt the chocolate and heat it to the proper temperture then stir it to cool it down and add the "seed" chocolate which was a solid piece of the same kind as the melted chocolate (i.e. semisweet chocolate seed into melted semisweet chocolate). The melted chocolate "copied" the stable crystals in the solid chocolate and aligned themselves correctly.
Annika gave us a "syringe" that we plunged into the pool of tempered chocolate in the chocolate tempering machine and once we filled the syringe, we emptied it into the molds. Each syringe had to contain a certain amount so that each bar is made with the same amount of chocolate. The molds are placed on a vibrating machine so as they're filled, the vibrations even out the melted chocolate so the molds fill evenly.
Once the molds are filled, they're left to cool then are packaged up. As part of our tour, we each got to fill 3 chocolate bars worth of molds which we marked with our names. Annika packaged them up once they were cool and we got to take them home with us.
The finished product - Cotton Tree Chocolate. I was hot and sweaty so clearly I wanted to go back into the tempering room :).