OpenSCAD script to make lots of M3 size spacers

gistfile1.txt

module spacer_m3($height)
{
    rotate([90,0,0]) 
    difference()
    {
        cylinder(r=5.5/2, $fn=6, h=$height);
        translate([0,0,-$height/2]) cylinder(r=3.2/2, $fn=60, h=$height*2);
    }
}

for (i = [0:7]) 
    {
        translate([i*10,0,0]) spacer_m3(30); 
    }

for (i = [0:7]) 
    {
        translate([i*10,20,0]) spacer_m3(15); 
    }

for (i = [0:7]) 
    {
        translate([i*10,30,0]) spacer_m3(5); 
    }

for (i = [0:7]) 
    {
        translate([i*10,30+25,0]) spacer_m3(20); 
    }