line from 4 corners marking-out BL, this is the hardest part of profiling as the lines has to be in right angle, using 345 method we did have to play around with the lines a bit moving it left or right on the batter board to get it right.

A better I thing is to make one corner in right angle first then do the other 3 after, once a line is moved always have to come back and check all other lines again.