$fn=270;
DA=54;

difference() {
  union(){
    import("./spool_desicant_and_hygrometer_holder-lid.stl", convexity=10);
    translate([DA/2,DA/2,-4]) cylinder(h=8, d=DA);
    translate([DA/2,DA/2,-4]) cylinder(h=2, d=70, center=true);
  }
  translate([DA/2,DA/2,-3]) union() {
    cylinder(d=46, h=7);
    cylinder(h=15, d=41.5, center=true);
    cube([43,7,15], center=true);
  }
}