local baseheight = 20

function placeRing()
  turtle.up()
  turtle.turnLeft()
  turtle.placeDown()
  turtle.forward()
  turtle.placeDown()
  turtle.forward()
  turtle.turnRight()
  turtle.forward()
  turtle.placeDown()
  turtle.forward()
  turtle.placeDown()
  turtle.forward()
  turtle.placeDown()
  turtle.forward()
  turtle.turnRight()
  turtle.forward()
  turtle.placeDown()
  turtle.forward()
  turtle.placeDown()
  turtle.forward()
  turtle.placeDown()
  turtle.forward()
  turtle.turnRight()
  turtle.forward()
  turtle.placeDown()
  turtle.forward()
  turtle.placeDown()
  turtle.forward()
  turtle.placeDown()
  turtle.forward()
  turtle.turnRight()
  turtle.forward()
  turtle.placeDown()
  turtle.forward()
  turtle.turnRight()
end

function buildBase()
  local curheight = 0
  while curheight < baseheight do
  	placeRing()
  end
 end

 buildBase()