You have created your stained glass pattern. Now you need to transfer it to the glass and then join the different pieces together. The most frequently used method for joining the different pieces is achieved by soldering. For you to do this on your own, you must at the minimum, have a soldering iron, adequate quantity of copper solder and flux. You would also need pre-cut adhesive copper strips.
If you cannot obtain pre-cut strips of the required dimensions, you can buy one or two copper sheets whose size should roughly match the length and width measurements of your glass pieces. Order a little extra to factor in waste.
Prior to doing the actual soldering, all edges must be cleaned thoroughly. Dust particles trapped within the solder would weaken the joints over time and even lead to a distorted and uneven window surface in extreme cases.
Next thing you do is to plug the soldering iron into the power supply to give it time to heat up to the appropriate temperature. As you do this, set out the copper strips on the glass edges. If you did not succeed to obtain strips from the hardware store, then take time to cut the copper sheet into strips that slightly exceed the length, width and thickness of the glass. The copper sheet is very thin and a set of tailoring scissors should be able to cut through cleanly.
After preparing the copper strips for the glass, pull away the paper back to expose the side with the glue or other bonding agent. Append the copper strip all round the glass edge making sure that the excess ends flow onto the face of the glass. Use a pointed object such as a bread knife or spoon to push in any irregular sections.
If you do not correct these sections, they will be visible after the soldering is complete and will give an untidy look to the final product. Brush the flux on either side of the copper foil. The flux is very important before soldering as it serves as second level of surface cleaning. Flux removes oxides from the surfaces of the metal pieces being joined to ensure a strong final bond is achieved.
From here, you now get into the actual soldering process. Different experts recommend varied techniques to achieve the best finish. The underlying principle is that you must be careful when doing the soldering because undoing a poorly soldered can leave the glass looking messy especially if addressed long after the solder has dried.
One of the best ways to do it yourself is by first moving the end of the heated copper solder as close as possible to the copper strip. You must be careful not to touch it though. Once you have done this, use the soldering iron to touch the copper solder piece so that the molten metal drops onto the gaps between the strips.
Move gently all around but do not be too slow as cracks may appear on the joints due to large variance in temperature at the joints. Once you are done, make sure you move the soldering iron away from the solder piece. Allow for cooling and there you have your joint.