wrote in message
...

survey twine and two bricks. the twine comes in dayglo colors. the
bricks are red. if you need more visibility, paint the bricks dayglo
too.

wrap the twine around the brick two or three turns and stretch it
where you need it.

I second that motion. Essentially the same thing masons do when laying
blocks, except on a smaller scale. Works for them, should work for the OP.
--

-Mike-