RichE
I was reading in recent issue about using Elmer's glue to create instrument glass. While shopping I found Elmer's CLEAR. A small dot off a toothpick settles and spreads into a crystal clear circle and several days later it is still flexible.
On larger gauges, I use Bondic (hardened by UV led). The key is to get just the right amount to achieve a level, or domed surface. These are large gauges on the Mifistofele model.
https://media.fotki.com/2v2JMb1KhxBoFJC.jpg