2.5 and inside on the vover hag a piece of of cotton fabric so the bee dont land on hard surface I have seen dome in the old county with foam . Not styrofoam and on top a sliding gate
To control the air flow ( mandatory) you can block the outtake or air flow by stapling some scotch brite material to prevent the bees from
Beeing chewed or escape , one company make solid reliable valve powerteck available at most good wood working shop or God forbid amazon . If you. Have the plywood ,you can come over we can cut them and assembled them together .this is what the control valve look like . Joel
