Rick,
Here is an idea for you. At Lowes they have some relatively low density cement board called Hardie Board that is quite cheap and used as a backer for ceramic tile. Get a piece of that and some nichrome ribbon. Drill a pattern of holes that allows you to run the wire from one side to the other, down through a hole to the back side and back up to the top for the next row. You could use a dremel to slot between holes on the back slightly so the wire doesn't stick out. You'll need to calculate the resistance of the wire needed at the voltage you want to use and then layout the pattern so that is how much wire is used. You then set your glass plate on top. If you want more uniform heat you may want an aluminum heat spreader over some thin insulation paper, then the glass.
Here is an idea for you. At Lowes they have some relatively low density cement board called Hardie Board that is quite cheap and used as a backer for ceramic tile. Get a piece of that and some nichrome ribbon. Drill a pattern of holes that allows you to run the wire from one side to the other, down through a hole to the back side and back up to the top for the next row. You could use a dremel to slot between holes on the back slightly so the wire doesn't stick out. You'll need to calculate the resistance of the wire needed at the voltage you want to use and then layout the pattern so that is how much wire is used. You then set your glass plate on top. If you want more uniform heat you may want an aluminum heat spreader over some thin insulation paper, then the glass.