窗帘导轨轮小柱

 实物

difference(){
 union(){
  cylinder(1, 3.5, 3.5, $fn=360);
  cylinder(8, 2, 2, $fn=360);
 }
 
 rotate([90,0,0])
 translate([0,6,-3])
 cylinder(6, 1, 1, $fn=360);
}