$fn=100; difference(){ union(){ linear_extrude(height = 8, center = true) import("pen_top.dxf"); rotate([90,0,0]) cylinder(r=4,h=14, center=true); translate([0,-4,0]) cube([15,8,12]); } rotate([90,0,0]) cylinder(r=2,h=16, center=true); translate([60,0,0]) rotate([0,90,0]) cylinder(r=2,h=16, center=true); }