I wish I had known this in July! LOL I have the heavy glass from our old Clear View windows that were in the farm house. I use them for shelves at our quilt show. We put 2x4's under them and can store extra pies there so that we can see them as we serve the pies that are lined up on top of the glass.
I also have written a "Tip" for our quilt club list that includes: Never let your cutting mat near anything hot; that includes your iron, hot water, your coffee cup, your hot car nor the sun from your window.