I don’t have any proprietary designs. I work to the traditional Martin and Gibson designs. I may, however, do a little bit of fiddling. For instance, I add an extra ¼” to the depth of my OM for some added bottom end. I call it a MOM, for Modified OM. My actual mother somehow didn’t find that nearly as amusing as I did.
I use french polish for the whole guitar. Top, back, sides, and neck. Yes, it’s a labour-intensive pain in the butt, and yes, it’s the best finish you can put on a guitar.
I use solid linings rather than kerfed linings. They stiffen the sides substantially and make it easier for the top and back to work together.
I use hide or fish glue on all sonically significant joints. It’s widely accepted that animal protein glues dry to a very brittle state and transmit vibrations better than other glues.
I know that people say you can’t “hear” what kind of glue has been used, and they’re right. But let’s say that hide glue improves the efficiency of the sound box by 3%. Then let’s say you stiffen the neck (another 3%), and the sides (another 3%).
All of a sudden, you’ve made your instrument almost 10% more efficient, and that’s something you can hear.
Someone once used the analogy of olympic athletes taking advantage of every little edge, to the point where, for example, swimmers would shave all the hair on their bodies.
I think the really first-rate guitar builders do the same. I think they use whatever tricks or techniques they can to eke every bit of performance and responsiveness out of their materials.
Otherwise, why not buy a factory guitar?