I make this image for one article on drugs and beasts. Snails really are alcoholic gasteropods! I buy a picture in iStock and use for background in LW. Next I model a beer mug with similar size and form and load a glass texture with a big refraction index. I buy also the magnificent Snail LW mesh of 3dCat http://3dcat.net/shop/shop.html and make a scene with some snails and my beer mug in same position and camera Zoom that original picture. I render the mug with the snails and finally I make in photoshop the composition.