Heated build plate (pre-) mounted

Birds-eye view of the build platform
Today I mounted the build platform, to check for dimensions and fit of the heated build plate PCB. Looks good. I need to increase the diameter of the mounting holes to compensate for the thermal expansion of the heat bed PCB. I am still looking for a viable insulator material between the heat bed and the wooden carrier plate.

Side view
Also, I need some good idea on how to mount the glass pane onto the build plate.