$fn =100; 
difference(){
union(){
minkowski()
{
  cube([40,14,1]);
  cylinder(r=2,h=1);
}

translate([1,1,0]) minkowski()
{
  cube([40-2,14-2,1+0.5]);
  cylinder(r=2,h=1);
}

translate([20,14/2,0])cylinder(d = 6.4+3,  h = 3);
translate([20+(6+2),14/2,0])cylinder(d = 6.4+3,  h = 3); 
translate([20+(6+2)*2,14/2,0])cylinder(d = 6.4+3,  h = 3); 

// inlay() 

translate([8,14/2,(15/2)-(9/2)])rotate([0,-15,0])cylinder(h=9,d=6+3, center= true);
}
union(){
translate([8,14/2,(15/2)-(9/2)])rotate([0,-15,0])cylinder(h=9+4,d=6, center = true); 


color(c=[0,0,255],alpha = 0.5){
translate([20,14/2,-0.5])cylinder(d = 6.4,  h = 7); 
translate([20+(6+2),14/2,-0.5])cylinder(d = 6.4,  h = 7);
translate([20+(6+2)*2,14/2,-0.5])cylinder(d = 6.4,  h = 7);
}
}
translate([0,0,-5])color(c=[255,0,0],alpha = 0.5) cube([40,14,5]); 
}