I have on piece of glass for the Otoneg 2 negative carrier. It's an Otoglas AN anti-newton glass, and fits in the top of the negative carrier. As near as I can figure out, the bottom glass is a special glass from Durst, which I'm unable to find. Can I use regular glass if I can find something the right thickness (which may be an unlikely find), or is there such a thing as optical glass sheets? It's 6 inches wide (15 cm) by 4 and 15/16ths (12.5 cm) wide and is beveled on all 4 sides. The sheet I have is close to 2 mm thick.