my question is about custom items. I would like to make a special gear for one of my NPCs, which would consist custom items. However, I did not find any possibilities to add them to the gear. How does it work? Can I do it?
Your only option is custom images for gear the NPC can wear. Look for existing items that fit in the desired slots and more-or-less look like what you want the special gear to be. But yeah talk to the Art Monkies about what you have in mind and they'll point you to the right 'existing entities' to apply customs to.