|An example where the fruit and leaves are all plated|
Build the flat, single thickness window first. This provides a solid panel to work on. It also enables you to see whether you really need the plating, and if so the exact areas where it will be applied.
You should solder the whole panel except where the plate is to be soldered. In this/these areas just lightly tin the back, although you will have already put a solder bead over the whole of the front.
Patina the back of the panel, except where the plate is to go. Allow this to dry and clean up any spills, especially in the neighborhood of the plating.
Foil the plate with a backing to match the colour of the patina. So use copper-backed foil where the panel is in copper patina, but black-backed where the patina is black.
Tin the foil on the plate with solder. If the piece is to cross a number of the base pieces, you need to patina the tinned face that will be placed toward the viewer with the same colour patina. You need to make sure this is absolutely dry before proceeding.
Clean the plate and the base glass where the plate is to cover very well. Make sure there are no oils or tarnish on the solder, and that everything is dry.
Solder the plate to every seam that it contacts with no flux and a small amount of solder. This is to insure there is no leakage of flux - by not using any - or solder between the two pieces of glass.
Put a small amount of clear silicone between the edge of the plate and the base glass where you were not able to solder. Just lightly fill the gaps to ensure a seal against moisture and insects.
When the silicone has cured, carefully patina the plate so no fluid seeps between the glasses.
Protect the uneven back when handling by placing a soft foam pad, or a polystyrene sheet with cutouts for the plating, on the back to protect the panel from the carrying board.