Turtle Builder: Cactus Farm 0.6

-- Slot 1: Cobble
-- Slot 2: Sand
-- Slot 3: Cactus
-- Slot 4: Fence
local cactusPerTower = 3
local towerHeight = cactusPerTower*4
local i = 0
local e = 0

while(e<2) do

while(i<cactusPerTower) do
turtle.select(1)
turtle.placeDown()
turtle.up()
turtle.select(2)
turtle.placeDown()
turtle.up()
turtle.select(3)
turtle.placeDown()
turtle.up()
turtle.select(4)
turtle.place()
turtle.up()
i = i + 1
end

turtle.forward()
turtle.forward()

i = 0
while(i<towerHeight) do
turtle.down()
i = i + 1
end

e = e +1
end