rs=3;
rc2=1;
rc1=1;
a=20;
$fa=0.5; // default minimum facet angle is now 0.5
$fs=0.5; // default minimum facet size is now 0.5 mm
for (angle = [0 : 120 : 240]) {
	rotate ([0, 0, angle]) {
		translate (-a/6*sqrt(3)*[1,0,0]) {
      	rotate ([90, 0, 0])
				cylinder(r=rc1,h=a,center=true);
			translate ([0,0,a*sqrt(3)]) rotate ([90, 0, 0])
				cylinder(r=rc2,h=a,center=true);
		}
		translate (a/3*sqrt(3)*[1,0,0]) {
			sphere(rs);
   		cylinder(r1=rc1,r2=rc2,h=a*sqrt(3));
   		translate(a*sqrt(3)*[0,0,1]) {
				sphere(rs);
   			rotate ([0,-90+atan(sqrt(2)),0])
					cylinder(r=rc2,h=a);
			}
		}
	}
}
translate (a*[0,0,sqrt(3)+1/3*sqrt(6)]) sphere(rs);
//translate (a*[0,0,sqrt(3)+1/12*sqrt(6)]) sphere(6);
//translate (a*[0,0,sqrt(3)+3/12*sqrt(6)]) sphere(4);