With a hammer and nails. No seriously, there is very little magic to it at all. First, a repeating pattern should be avoided at all costs. Repeating widths represent a 1960’s (ranch plank) attempt at a wide board floor but in no way duplicate an early floor. As your flooring arrives strapped in bundles of uniform widths, it is easy to tell at a glance how much of each width you’ve received (along with reviewing the tally!). The layout is no more scientific than using rows of more prevalent widths more frequently and less prevalent widths less frequently. For example, in a 3″ – 6″ random width pattern, you may receive: 10% 3″, 30% 4″, 40% 5″ and 20% 6″ . Therefore, your layout may look like this: 5″, 4″, 5″, 6″, 5″, 3″ 4″ 6″ 5″, 4″, and so forth; or something like that. This is not nearly as difficult as it may seem, and it prevents the eye from picking up a pattern and most closely resembles an historic floor.