CC: tofu5

-- tofu5
--  surround four directions with walls

turtle.up()  -- move up

-- stack three squares
for ronoji=1,3 do
  -- make 4 sides of a square
  for hen=1,4 do
    -- put 4 blocks in the ground
    for i=1,4 do
      turtle.forward()  -- move to next position
      turtle.placeDown()  -- put a block
    end

    turtle.turnRight()  -- turn 90 degrees to the right
  end

  turtle.up() -- move up
end