Hello. I am from Romania and Covid19 is spreading fast (10-15 new confirmed cases per day, already 95 cases now). No protection masks can be found in the country and I found some 3dprintable masks on Thingiverse. I do not know what material to use for a changeable filter in order to obtain best protection (something comparable with N95 or FFP2). Some people use cafe filters, paper towels etc. I read that medical masks are made of cotton, non-woven fabric.Do you have any experience? Thank you.