The use of Cortosis will be very very limited on this site, On average, I hope to see at most 5 in 150 characters using any kind of cortosis, whether it be in a sword or armor. Cortosis itself is a very rare material.
There are a few different types of cortosis, and some different effects from the metal. On this board, the effect of cortosis coming into contact with lightsabers is: IT WILL NOT DEACTIVATE THE LIGHTSABER, but merely be able to stand against it. Even if the lightsaber did deactivate against the cortosis, it wouldn't be for more than a matter of seconds.
Those wishing to have a material, must first check with me, but it will be unlikely that you'll be one of few able to acquire some sort of Cortosis armament.
Substitutes for Cortosis:
Beskar (mandalorian iron) - Metal Used by Mandalorian's for Armor and ships.
Non-Mandalorians can not have this, since it's only found on one planet in the entire galaxy, and the Mandalorians have a monopoly on it.
Neuranium - A metallic substance used to shield from radiation, and one of the heaviest and densest metals in the galaxy. A millimeter of it could stop most scanners, and it could even temporarily block lightsaber energy. However in order to cover a space as large as a cargo hold, it would be prohibitively heavy and thus inefficient to use. Neuranium was so dense that some gravity-sensitive species noted its warping of the space-time fabric of gravity itself that a large piece created.
Phrik - like cortosis, was a rare metal that could withstand the potency of a lightsaber blade, although unlike the aforementioned metal, Phrik did not possess the ability to cause the blade to short out. Phrik was most notably used in the construction of the electrostaffs.
Ultrachrome - Ultrachrome was a metal used as starship armor around the time of the Great Sith War. Silver and superconductive, it reflected blaster and slugthrower weaponry, could not be cut by a lightsaber, and was immune to metal-eating fungi.