Plug in a 100-watt soldering iron and set it in its holder stand on flat wood or metal table. Wash your cut glass pieces in a sink while the iron warms. Dry all glass pieces with a clean, soft cloth.
Wrap 7/32-inch black-backed copper foil around the edges of all glass pieces. Press foil down on either side of glass piece faces. Arrange glass pieces into your pattern on your work surface next to the soldering iron.
Brush all exposed copper foil with stained glass flux and a small horsehair brush. Unroll a piece of 60/40 solid core solder and touch the tip of your soldering iron to it so that it melts and covers the tip of the iron with a trace amount of solder.
Hold the solder about 1/4-inch above the copper foil at the top left corner of your stained glass picture. Melt the solder with your soldering iron so that it covers the foil lines. Follow the copper foil lines carefully, laying a thin, even straight line of solder over all copper foil. Let the project sit for 60 minutes.
Flip the picture over. Brush all copper foil with flux and melt solder over all foil lines. Wait 60 minutes and flux and solder the edges of the picture. Wait 60 more minutes and rinse picture off in sink. Dry with dry, clean cloth. Hang your picture where desired.