wedge_thickness = 2;
slots_x = 4;
slots_y = 4;

x_outside = 56;
y_outside = 68;

outside_offset = 2;
outside_offset_seat = 1;
seat_width = 1;

union(){
    linear_extrude(2){
        difference(){
            slot_width = (x_outside - 2 * outside_offset - (slots_x-1)*wedge_thickness) / slots_x;
            slot_height = (y_outside - 2 * outside_offset - (slots_y-1)*wedge_thickness) / slots_y;
            square(size=[x_outside, y_outside], center=false);
            translate([outside_offset, outside_offset, 0])
            for (i =[0:slots_y-1]){
                for (j = [0:slots_x-1]){
                    translate([j*(slot_width+wedge_thickness), i*(slot_height+wedge_thickness), 0])
                    square(size=[slot_width, slot_height], center=false);
                }
            }
        }
    }
    linear_extrude(5){
        translate([outside_offset_seat, outside_offset_seat])
        difference(){
            square(size=[x_outside-2*outside_offset_seat, y_outside-2*outside_offset_seat], center=false);
            translate([outside_offset_seat, outside_offset_seat, 0])
            square(size=[x_outside-2*outside_offset_seat-2*seat_width, y_outside-2*outside_offset_seat-2*seat_width], center=false);
        }
    }
}