at the moment you can´t do any weapons or items at all.
In the future you might be able to do some items on your own. If you have the needed materials for it ofcourse. But when, and even if, it will be possible is hard to say.
first we will have basic items, that anyone can buy from NPCs which shouldn´t take that long for us to get.
After that there is production of items and then finally maybe R&D and creation on your own