First of all a big part of doing a window is installation. You have to think about it. If you want it to just be hung within a window frame it has to be able to work for hanging and to support itself in terms of strength and quality of material. You have to think about the background, do I have trees in the background, do I have sky in the background, and is a lake there? It has to be that whatever you design will work with the background because that background is eventually going to come into the window since you can see through the stained glass. The light and dark are important features of your design.
In terms of the structure, you design a window and use lead to hold the glass together, but the lead actually adds strength to the structure of the glass and integrity to the overall design. So you have to design little pieces next to large pieces, the large pieces will strengthen the small ones. So this pattern evolves. You have to take small areas with large ones to give the overall design strength in how you see it as a viewer and how the glass is within the structure of the window.
You have to think about support. If it is a large window, you have to put support bars in it. When you are designing the window sometimes you have to design the support bars in it before you design the window. You must create a grid for your window to fit within especially if it is a large window, otherwise it can fall apart. We don’t want any accidents when we are doing our work. So all of these design elements come together when designing a stained glass window.