include <BOSL2/std.scad>

in_d = 9;
t = 2;
zip_t = 0.75;
zip_w = 7.5;
zip_n = 3;
zip_dist = 15;
height = 60;

$fn=36;

difference() {
  cyl(d=in_d+2*t, h=height, rounding=1);
  down(0.01) cyl(d=in_d, h=height+0.02, rounding=-1);
  for(i = [0:1:zip_n-1]) {
    up(-(height-zip_dist)/2 + i*(height-zip_dist)/(zip_n-1)) difference() {
      cyl(d=in_d+2*t+0.01, h=zip_w);
      cyl(d=in_d+2*t-2*zip_t, h=zip_w, rounding=-1);
    }
  }
  cube([100,1,100], center=true);
}