Sticky bottom.

next I tidy up my frames and cut some holes. Often people think this is to lighten the board which it can do. But more important is to ensure air flow throughout the board. Because my boards are hollow, the air inside expands when it's hot and contracts when cold. Hence the need for a vent. I've also made a bottom for the board which as you see in the photos is like a sheet, glued and clamped and left for 24hrs. Then I attach the frame to the bottom.