module tower(radius, height) {
  // groove = .75;
  // target_brick_width = 10;
  // target_brick_height = 5;
  // brick_depth = 5;
  circum = 2 * radius * PI;
  bricks = floor(circum / target_brick_width);
  brick_width_deg = 360 / bricks;
  rings = floor(height / target_brick_height);
  brick_height = height / rings;
  $fn = bricks;

  module ring(n) {
    start_deg = 0;
    end_deg = brick_width_deg;
    translate([0, 0, -1]) {
      if (n > 1) {
        // Left groove
        for (i=[0:bricks]) {
          translate([radius * cos(brick_width_deg * i), radius * sin(brick_width_deg * i), 1]) {
            rotate([0, 0, 45 + brick_width_deg * i]) {        
              cube(size=[groove, groove, brick_height], center=false);
            }
          }
        }
      }
      
    }
    // Bottom groove
    rotate_extrude() {
      translate([radius * cos(start_deg), radius * sin(start_deg)]) {
        rotate([0, 0, 45]) {
          square(size=[groove, groove], center=true); 
        }
      }
    }
  }

  module loop(n) {
    if (n > 0) {
      union(){
        ring(n);
        rotate([0,0,brick_width_deg / 2]) {
          translate([0,0,brick_height]) {
            loop(n - 1);
          }
        }
      }
    }
  }
  difference() {
    cylinder(r=radius, h=height, center=false);
    translate([0,0,-1]) {
      cylinder(r=radius - brick_depth, h=height + 2, center=false);
    }
    if (!draft) {
      loop(rings + 1);
    }
  }
}