3mm (.118 in) i believe. I picked it up at lowes. It was by far the most expensive part of the setup. However, my next enclosure will be noise cancelling. These hollow tables make for great drums and echo vibrations hundreds of feet. I've since added neoprene to cover the bottom inside and out, and tons of weather stripping which has helped but the noise is just transferred by the acrylic. Especially when I put the table legs on the bottom, that is when it's the worst.
it's acrylic not glass
and appliance "feet" to quiet washers, and fridges, and stablizers around the legs, motor dampeners etc etc.
What is the thickness of glass?