There are two people I can highly reccomend for Kydex knife scabbards.
The first is Frank Sigmond. He works with kydex and nylon. He has the most extensive line of real world deisgns in use by a lot of the Military Special Operations Community. His systems have been in use around the world and stand the test of time. He makes the original scabbard system for the Carson U2.
He can be reached at:
Edge Guard Tactical Carry System
P.O. Box 589
Granite Falls,NC 28360
Phone: 828-396-1266 Fax: 828-396-9880
The other person I can reccomend is Frank Olesen. He makes knife scabbards and tactical kydex for pistols and accessories.
His work is being used by numerous Federal law enforcement organizations and Marine military units as well as several tactical knife makers.
He can be contacted at:
P.O. Box 8422
Spokane, WA 99203