It's absolutely crucial that masks actually filter out very fine particulates. N95 masks are rated to filter out >=95% of 0.3 micron particles. You probably have the stock to make something close enough to a typical surgical mask, but that's not going to protect the wearer from Coronavirus, at best it would prevent a contagious patient from spreading it. You also need to form the mask such that the edges will seal against the face. I doubt you have suitable filter media on hand, and tight woven fabric will not cut it here. It's significantly harder to trap virus laden particles in the air after they've dried out, so coarse filter media is only going to be effective if it's right in front of the source where the breath is still hot and humid.