OpenScad_Designs/rod.scad

diam = 12.5;
difference()
{
    translate([0,0,4.5])
    rotate([90,0,0])
    cylinder(r=diam/2, h=200, center=true, $fn=100);
    translate([0,0,-250])
    cube(size=[500, 500, 500], center=true);
}