Version 2: Improved fit around chin.
Having tried someone else's mask I noted that with a HEPA filter it was very hard to suck air in and as I am an RN I knew it would just be too tiring to wear for a long period. So I made this model with TWICE the surface area so it should only take half the effort to breathe with my version. I hope you do not need one but if you do I hope it works well for you. You can scale the mask to 95% or 90% to fit most people but some may want 85% of full size. Just remember to scale the filter frame to fit. I recommend you find brand new vacuum cleaner bags rated for HEPA standards. If you find some made from cloth you can even wash them and reuse them if you need to. The corners of the frame are made to allow excess material to fold into them without causing it to bunch up. Stay safe. No guarantee is given that this design will keep you from getting an air borne illness. If you use filter material that is not suitable and end up breathing lint and fibres then I am not responsible.
No support is needed.
The author hasn't provided the model origin yet.