The Centers for Disease Control and Prevention says healthcare workers should weear homemade mask as a last resort when no protective equipment is available. They are also recommending that people start wearing masks while in public.
You might have some items around the house that you can use to make a mask. The chart below will help you figure out the effectiveness of these items.
If you are crafty and want to make your own check out the video below. If you are not as crafty you can use a old t-shirt or a bandana as a mask.