Do you need a face mask?  Do you have a bandana?  If you said yes, to both questions, we have a solution for you.  Oh, one more question.  Do you have rubber bands?  You will need two of those in addition to your bandana.

Note: if you don't have a bandana, you can obviously use another material.

What is the difference between a bandana and handkerchief?

What are the best protective face mask materials?

Note: a DIY face mask does NOT have the same benefits as a N95 respirator mask.