I am an amateur wood worker (I have built 2 so far and they work but are by no means perfect). The two I have built I used a router to create an inset on the inside of the hive, and then used self tapping sheet metal screws with flat tops to screw the plexiglass into the hive side. This works fine, however it creates a gap between the false backs and the observation window, enough so that bees can sequeak by. To solve that problem, I used some of the screen material and attached a small "puffy" section of it to the front side where the window is of the false back to the back side of the false back on the window side... Poor ASCII graphics:
| | |
So, it creates a wiper effect and the bees cannot pass. This works, but I don't like it. The |---------| is the false back looking from the top down on it. The /, | and \ characters make up the "screened wiper" I am speaking of.
What method do you use to put in the observation window? I have another one to build before Wednesday and would like to use a better method.