Ultimaker Heated Bed

This fits into the screwholes of the Ultimaker Z-carriage.
http://www.youtube.com/watch?v=zAHgWbq04nk

The glass can be mounted using the smaller holes, e.g. by some small wooden piezes having a 3.2mm hole.

The glass plate should be 22x24 cm to fit in there. The sides will overhang, but I could not find larger double sided FR4 PCBs than 30x20cm.
I also recommend to diagonally cut away the glass corner over the minx-miny corner, where the pcb has the dent, to have initial through-extrusion