$length = 100;
$diameter_slider = 5;
$diameter = $diameter_slider + 5;
$slack = 0.6;
$stopper = 3;

$fn = $preview ? 32 : 64;

rotate([0,90,0])
cylinder($length, $diameter_slider/2, $diameter_slider/2);

rotate([0,90,0])
translate([0,0,$length - 0.001])
cylinder($stopper, $diameter/2, $diameter/2);