Tip 5: Got a Glass? Get a Postcard
One of the most impressive of Photoshop's 3D capabilities is the way it renders glass objects, complete with reflections and refraction. But unless you give Photoshop something to refract, the object will never look realistic.
Choose a background scene, and rather than simply placing it on a new layer behind the 3D layer, use 3D > New Mesh from Layer > Postcard instead; then merge the two layers together into a single 3D layer (see Figure 5). The glass object will now refract the postcard object when you render the scene.
Figure 5 Turning a background into a 3D postcard allows you to refract it in transparent objects.