Kydex or Concealex?
I'm often asked what the difference is. They are two different plastics. Both are used for molding, both come in various thicknesses. Kydex has been around for years, with some of the first sheaths appearing in the 70's. Kydex and concealex are both "thermoplastics", meaning they must be heated to become pliable for molding.
Kydex is PVC based Acrylic, Concealex, which is a name invented to sell products, is better known as Boltoron, and is ABS based.
Which is better? I like the "Concealex" because it's easier to work with, grinds better, and has better resistance to heat and cold, where kydex gets brittle. I don't buy kydex, but the name has stuck as a generic for any synthetic sheaths or holsters.
I'm not sure who started doing sheaths first, but I do now it goes back to the 70's at least, so it's fairly old technology by now.
Survival Sheath Systems
"Failing to prepare is preparing to fail."