This is a flexible filter mask developed in response to acute PPE shortages due to the Covid-19 coronavirus pandemic. It was prototyped in Ninjaflex brand 95a durometer flexible filament (for flexible areas) and PETG plastic filament (for rigid areas). It is a prototype that was used to guide later production in SLS 3D printing and injection molding. There are significant concerns about the appropriateness of FDM printing processes for this application, so FDM is not presently recommended, but is being investigated further. This design has evolved to include small, medium, and large mask body sizes. All mask bodies fit the same filter body compnents. The mask body is flexible, the filter housing components are rigid. The shape of this mask, particularly where it meets the face, is derived from the "Stopgap Surgical Face Mask", but has been altered to allow for FDM prototyping without support material in flexible material.