Compress

n = 64
while true do
  low = false
  turtle.select(1)
  for i = 1,12 do
    if (turtle.getSelectedSlot() == 4 or turtle.getSelectedSlot() == 8 or turtle.getSelectedSlot() == 12) then
      turtle.dropDown()
    else
      turtle.suckDown(64-turtle.getItemCount())
      if turtle.getItemCount() < 64 then
        low = true
      end
    end
    turtle.select(turtle.getSelectedSlot()+1)
  end
  if low==true then
    for i = 1,12 do
      turtle.select(i)
      turtle.dropDown()
    end
    print("Not enough cobble. Sleeping...")
    sleep(600)
  else
    turtle.craft(n)
    turtle.dropUp()
  end
end