If you take a look at the wings and body in the picture to the left, you will see a pattern that is entirely random. This is produced with the glue chipping procedure.
With the wings fully etched, a special glue is heated up, and with the vinyl stencil still in place, the heated glue is poured into the wing section, and any other areas where glue chipping is wanted. The while area should be covered entirely with paper so as to retain the shards of glass that get chipped off, as the glue dries and literally pulls tiny shards of glass away from the surface. This process takes approximately 24 hours.
After carefully brushing up the shards of glass captured within the paper, they can be thrown away, leaving the end result you see here.