1. CNC factory: PMMA plates must be cooled with cooling water during CNC milling process. While the PMMA panel is sprayed with cooling water, the panel's temperature is about 10 to 15 degrees Celsius. CNC manufacturers have not waited for the temperature up to 20 degrees to measure these first out samples which caused misjudement issues. 2. Pretech:The double-sided adhesive assembly jig is actually in accordance with the upper limit of the product, but the operator did not well pay attention that the plate must be placed in the jig in totally flat condition before assembling it with adhesive.(Even the panel humps a little bit , it still could be inserted into adhesive assembly jig.)