Chocolate – How to make modeling chocolate shiny

Chocolate which has been melted will look dull when cooled down again. Cocoa butter contains crystals, and when heating and cooling chocolate, there will form crystals of different sizes. Because of this, your chocolate look matt. You can use the technique of tempering chocolate to get great shiny chocolate. There will only form 'right' crystals with this technique. If you google 'tempering chocolate' you get lots of good results, which give you a better description of what to do then I can. For example you can use this sites description: http://candy.about.com/od/candybasics/ht/temperchoc.htm
Or this site which give the description using both Celcius and Fahrenheit: http://allrecipes.com/howto/tempering-chocolate/

You can try to make chocolate cups in general by "painting" a small dish/cup with chocolate, and letting it set in the fridge. If you want tempered chocolate, there are techniques for that.

But in any case, you've got to consider that different chocolates have different heating/cooling rates, so mixing chocolates with different fat contents (like milk vs dark), or from different manufacturers will (pardon the pun) fudge your calculations a bit as far as how hot/cool the chocolate needs to be. And white chocolate is an entirely different beast, so it has its own melting/setting points to consider as well.