We have discovered the next Tolkien... for the detail and not because he's a fairy.

Moke, not to rain on your reign… a very comprehensive list of available blank types… hell, most of those blank types I’ve never heard of let alone try to pronounce, however, these could be a couple that may be camouflaged 
 
in your technical synopsis and some prospective turners may explicitly seek them out by their more basic characteristics.
 
Antler:
a pain to get a long straight piece for some tubes.  Don’t be afraid to reveal live edges,
All my antler based pens with live edges were first to be snapped up.
 
Buffalo horn:
Some are totally black, while others have some streaking… dogs love the shavings like with the antler.
 
Snakeskin:
Have tarnished (yellowed) being locked up for 17 years.  Recommend buying the blanks… not catching and making your own.
 
Alternate Ivory: 
though may be resin based, they seem to be in a class of their own. Subtly different from white blanks.
 
Aluminium:
Pre cut for both Sierra and Cigar.  I've been told they can be processed on a wood lathe using good chisels, however, I haven’t turned a pen from it yet. Would look great with a chrome pen kit.
 
M3 Mokume Metal (Metal Composite Blanks):
Were some of my best/most expensive sellers (to executives).
 

If your first cut is too short... Take the second cut from the longer end... LBD