The next thing to think about is where on the billet the pattern is being formed.

Types of patterns. I break the different patterns into two families: Face grain patterns and End grain patterns. These refer to the position on the billet where the pattern is developed. (see attachment) 

There are some patterns that use the sides as part of the pattern, like an interrupted twist, but most of the typical patterns I can think of are developed on the faces or the ends.

Examples of face grain patterns are Raindrop, ladder, twists, and random. 
Examples of end grain patterns are W's, feather, and some mosaics.

There are patterns out there that use multiple bars to develop. The bars can be the same pattern (Turkish Twist is an example) or a combination of differently patterned bars joined to create complex patterns.

Understanding the basic mechanics of pattern development is the foundation of making PWS. Understanding that each of these patterns can be achieved through different methods, each method providing slight variations to the end product, is also foundational to creating PWS. 

For instance, ladder pattern can be created by pressing grooves and grinding down, or cutting grooves and forging down, or grinding grooves and forging down. Each method will produce a "ladder" with slightly different appearance than the others.

Understanding the different methods of manipulation also allows you to "think backwards" or reverse engineer to create a pattern. Looking at a pattern that someone else has created that you would like to reproduce, or drawing a pattern you would like to create, requires you to reverse engineer the steps from finished product to original billet or billets. 

Another more experienced maker could explain how they make a pattern to you, but without the foundational knowledge of how pattern manipulation is done, it would likely be gibberish. The best thing you can do to gain this knowledge is to experiment with pattern development, either in steel, or modeling clay.

Mr. States,

That has to be some of the best explaining on the fundementals of damascus that I have ever read. Thank you! If ever someone decides to write a good book on the subject, that should be the intro. I have seen that clay trick done in a book from scandanavia on damascus. My brother is a techy type and I have been after him to find me some sort of CAD program that could duplicate that idea but be a bit more controllable than some playdoh, no luck so far unfortuntley.

Padrick O'Grady

O'Grady Padrick for cheap stuff, you can use pottery clay.  My wife does pottery in her studio and its cheap from a local store, and for $50, you can get enough clay to test 6000 patterns.  Different clays have different color, but you can also add food coloring too.  I like the clay better than playdoh because its stiffer and doesnt deform as easily.

To keep it soft so you can reuse it, just keep it wrapped in plastic once you are done.  

A while back on this forum, MS Steve Culver posted a link to a software program called Thor II. It allows you to upload a jpeg file that is the end grain of your starting billet and put it through a twisting function and then a grinding function to see what it will look like.

https://www.americanbladesmith.org/community/advanced-damascus-steel/thor-ii-software-download/

Unfortunately that link is now broken, but I can provide a new link: https://web.archive.org/web/20190308174623/https://www.stahlundseide.de/html/thor_ii.html
It is in German, so that might be problematic.

However, I do have a copy available on my Google drive of just the software: https://drive.google.com/file/d/1AVPwQoa3cm3cqGcao0Rfvr1dnk9A42eB/view?usp=drive_link