Many of my ideas and methods have been copied over the years. The only protection I gave myself was owning all my brand names, which I still do to this day. It's easy to modify a cab after the first one has been built. As people well know by now, the original S118 was scaled up from the JBL 4530. I didn't have a problem with making a similar cab, because JBL publish the plans for constructors. As with the Fane hand book, JBL made plans available with the sole purpose of selling more chassis speakers.
Regarding making a lookalike, why not? I would like to think that over years I have inspired people to get up and do what I did.
One thing I would say, I think you learn less about box building when you have someone elses drawings. For me. experimenting was all the fun, I have ditched a few cabs in my time and knowing what not what to do is just as important as doing the correct thing.
Most of my design ideas have been logic. I have never used a program for anything apart from measurements.
Regarding the cab. Make sure it is strong and heavy. I am building RX's at the moment and next week start on the Mk2. (which will be bigger) Pictures will be posted in due course.