There have been a number of do-it-yourself (DIY) mask designs released and tested by both universities and other institutions on account of world wide Personal Protection Equipment (PPE) shortages. Some were designed at the time of the SARS epidemic, and use double-folded kitchen paper towels with tissue.
Even though double tea towel masks are more effective in reducing viral exposure, it's difficult to breathe with it on.
What design has been tested to provide relatively good protection while being comfortable to wear and breathe while wearing them? And it needs to use readily available materials throughout the world.