module tube_in(pd,p,n,w){   //internal tube

    pbr = resample_path(pd, n+1, closed=false);

   // echo(pbr);

    for (i=[1:1:n]){

       hull(){  

          path_copies(p, 1,1,pbr[i-1][0], rotate_children=true,closed=false) rotate(90,[0,1,0])translate([0,0,-0.08])cylinder(d=pbr[i-1][1]+w,h=0.1,$fn=tube_fn);

          path_copies(p, 1,1,pbr[i][0], rotate_children=true,closed=false) rotate(90,[0,1,0])translate([0,0,-0.08])cylinder(d=pbr[i][1]+w,h=0.1,$fn=tube_fn);

       }} }

I use hull for building curved tubes\ but when I try to replace “for” with chain_hull it does not work ``` module tube_in(pd,p,n,w){ //internal tube ``` ``` pbr = resample_path(pd, n+1, closed=false); ``` ``` // echo(pbr); ``` ``` for (i=[1:1:n]){ ``` ``` hull(){ ``` ``` path_copies(p, 1,1,pbr[i-1][0], rotate_children=true,closed=false) rotate(90,[0,1,0])translate([0,0,-0.08])cylinder(d=pbr[i-1][1]+w,h=0.1,$fn=tube_fn); ``` ``` path_copies(p, 1,1,pbr[i][0], rotate_children=true,closed=false) rotate(90,[0,1,0])translate([0,0,-0.08])cylinder(d=pbr[i][1]+w,h=0.1,$fn=tube_fn); ``` ``` }} } ```