We recently discussed this in another thread, but one of the low observability (stealth) characteristics of the F-117 was a reduced radar cross section (visibility) using flat sections of fuselage in a faceted manner.

This was calculated by hand by Skunk Works engineers. They didn't have the benefit of computerized physical modeling back then. They were able to reduce the radar visibility to a size about that of a bird (it's actually a little larger, iirc).

My understanding with Zoltan is that he just looked birds flying at 500-600mph. He claims that he invented all this complex, custom gear accompanied by advanced-sounding jargon, but the US military dismissed it as hyperbole (which Zoltan is known for).

The B-2 had the benefit of computer-aided physical modeling which explains it's lack of facets. The B-1 and B-52 also have low observability characteristics to reduce their radar and infrared characteristics (although they aren't known as "stealth" aircraft).

I think that stealth aircraft as we know them are largely obsolete. Hence, the increased focus on UAVs and satellites. I have some ideas about where to go next, but the costs would make the B-2 look like a Girl Scout cookie sale.

Disclaimer: I worked on many of the above-mentioned aircraft.