I am about to replace a printer bed with a piece of ATP 5 (MIC 6) Cast Tool Plate. The plate will be 16" square. It will only be supported at the very corners approximate 0.5" (1/2 inch) from each edge. The maximum unsupported weight (in the middle of the bed) is about 6 - 7 pounds (2 spools worth + plate glass + silicone heater). My choices start at 0.25" (1/4 inch) and proceed upwards in 0.0625" (1/16 inch) increments. What is the thinnest size plate I should be able to use with minimal sagging?