Now for the How-To:
My first step was a stained glass pattern brought into Photoshop. Using the Magic Wand, I selected each piece of glass and filled the area with solid black. I then inverted the selection and filled the rest with solid white. Each piece was saved as its own PSD in subfolder in the ZBrush Export/Import folder. The accompanying image shows the original, color coded to 6 of the resulting alpha maps.

Once I had all of my alpha maps, I finally started ZBrush. I created a Plane3D with super high density mesh and proportions the same as the alphas (which were all exactly the same size, of course). To do this, simply divide the shorter dimension by the larger dimension and multiply by 100. That will give you a value to plug into the H Radius or V Radius in the Tool:Modifiers:Initialize menu. In this case, I also set my main document up with the same dimensions. Anyway, save that tool!
Next, draw that plane on the canvas to the size and position that you want. Place a marker, and clear the layer.
The next step is to clone the tool and import a group of alpha maps. Selecting the first alpha map, go to the Tool:Modifiers:Selection and click the ALP button to mask your tool. Hide Points, clear the mask, and then activate your marker. The piece will automatically appear in exactly the right position. Repeat the process for every piece, using appropriate materials and colors (remember that stained glass often changes in color from piece to piece – even when the pieces are of the same type of glass).
When all of the pieces are placed, it’s time to create the lead. I used the SpheresBrush and a metal material with a low draw radius. It was just a matter of painting over the lines between pieces. It’s not desirable to be perfect with the lines, since lead never is.
For lighting, I dropped the ambient down to 2 and let the materials pretty much light themselves.

As for the materials, I’ve included a starter pack of 7 glasses. The main factors in creating them was that they have negative noise and a high ambient setting. When you use these, don’t be afraid to play with the noise radius, especially. Depending on your canvas size, it may need to be at all kinds of different settings to look right for your piece. It is also sometimes helpful to clone a material and change the noise radius a fair amount if two pieces are right next to each other. It’s not a good idea to have the pattern between two pieces match up. As you create your own, it’ll be easy for you to add them to the remaining 93 slots available in the pack.
Download the StainedGlass MaterialPack here. (380 kb)
Hope you have fun with it!