Clean the glass panel or window frame with rubbing alcohol and paper towels to remove any dirt and fingerprints from the work surface. Lay the panel flat if possible.
Protect the edges of the frame, if any, with painters tape; be careful not to adhere the tape directly to the glass. Position and tape the pattern to the back side of the panel or transfer the pattern to the back of the glass with a pencil.
Cut the tip of the grey acrylic caulk off with a sharp razor blade. Do not cut it off too low to avoid a large bead of caulk from being extruded. Match the size of the bead to the lead lines of the pattern. Insert the caulk tube into the caulking gun.
Create the lead lines of the pattern on the panel with the grey caulk, being careful to make fluid lines. When all lead lines are placed, use the razor blade to carefully remove any imperfections. Allow the lines to dry undisturbed for 24 to 48 hours.
Fill the open sections of the pattern with the various colors of silicone caulk. Silicone is more transparent than acrylic and will create a realistic stained glass look. Begin by placing a small amount of caulk in one section of the pattern. Use the stiff bristle brush or a finger to spread the caulk to cover the entire section. Experiment with the different applications to create the desired stained glass effects, such as smooth or rippled. Allow the silicone to dry completely. Drying times will vary depending on the thickness applied. The thicker the layer of caulk used, the less transparent the design will become.