Thank you! This really gave me some confidence. I used a more rudimentary method. Use a rigid scrap to measure the top of the crumb tray when partly inserted with a mark on the scrap. Remove the crumb tray and place your piece with a riser piece underneath to lift it around 1/4" above the crumb tray height. I wasn’t cutting, just etching. Mark the height of the surface of the piece to be etched on the same scrap. Measure the difference from the first line to the second line (convert to decimal on Google) and that is the number to be entered in your material thickness! Worked great.