$fn=12;

flagHeight=35;
flagWidth=25;
baseThickness=2;

gutterHeight=5;
gutterWidth=4;

translate([0,-gutterWidth/2,gutterHeight/2-gutterHeight]){
  cube([10,flagWidth-gutterWidth,gutterHeight], center=true);
}

translate([0,-gutterWidth,(flagHeight-gutterHeight)/2]){
  #cube([10,flagWidth,flagHeight-gutterHeight], center=true);
}

translate([0,-(flagWidth+20)/2,2/2]){
  difference(){
    cube([10,20,baseThickness], center=true);
    translate([0,0,0])
      #cylinder(h=4,r=2.5,center=true);
  }
}