Stained Glass Design

The term stained glass can refer to colored glass as a material or to works created from it. Throughout its thousand-year history, the term has been applied almost exclusively to the windows of churches, mosques and other significant buildings. Although traditionally made in flat panels and used as windows, the creations of modern stained glass artists also include three-dimensional structures and sculpture. Modern vernacular usage has often extended the term "stained glass" to include domestic lead light and objects d'art created from came glass work exemplified in the famous lamps of Louis Comfort Tiffany.

Firstly

The first stage in the production of a window is to make, or acquire from the architect or owners of the building, an accurate template of the window opening that the glass is to fit.

The subject matter of the window is determined to suit the location, a particular theme, or the whim of the patron. A small design called a Vidimus (from Latin "we saw it") is prepared which can be shown to the patron. A scaled model maquette may also be provided. The designer must take into account the design, the structure of the window, the nature and size of the glass available and his or her own preferred technique.

Make Sure...

Each piece of glass is selected for the desired colour and cut to match a section of the template. An exact fit is ensured by grozing the edges with a tool which can nibble off small pieces.

Then

Once the glass is cut and painted, the pieces are assembled by slotting them into H-sectioned lead cames. All the joints are then soldered together and the glass pieces are prevented from rattling and the window made weatherproof by forcing a soft oily cement or mastic between the glass and the cames.

Some stained glass works use lead came, which is a lead channel that holds pieces of glass together.  This is a completely different technique than I am showing you.  This technique uses copper foil which has an adhesive on one side to hold the glass pieces together.