You used to be able to get coffee bags from makers like Folgers. I tried them and they were thin and insipid. Apparently they were mostly instant cofffee with some ground coffee to improve the flavor, although I can testify they did nothing to improve the density of the drink. I am not sure if pouring boiling water over a homemade coffee bag would be enough to make real coffee. I will try it some time. Oh...maybe I would have to boil it for a minute or three in a pot? Of course that increases the fiddle time. I found a one cup permanent gold filter in Goodwill, but it does not fit most large cups including some I use for backpacking with a large mouth.