The contact in the Cebu City that @positive-mind and I make the 3D prints for hospitals and clinics for left me with a bit of a challenge the other day. 3M have have brought out a brought out a couple of face masks for medical staff the 3M 6502QL and a new full face mask 3M FF400. 
The big issue with both of the masks is the that the exhaust valve does not have a HEPA filter so any exhaled air will blow out unfiltered to the patient so not great for surgical and other medical procedures.
Most of the older masks by 3M the 6200 and 7500 series or the 6800 full face have been around around for a while and HEPA filter holders have been designed and you can easily find them on Thingiverse Unfortunately with these new masks the only option is to design something yourself.
Tackling the 6202QL first there are a couple of options. Fitting filter inside over the exhaust valve .
Or on the out side in the exhaust port.
After looking at the mask for a bit I think the external option would be better so I worked out this on Tinkercad
The insert is a complete new design but the filter holder is a scaled down version if the one we fit to the 3M 6200 looks fine and I think it will work.
The 3M FF400 was proving more of a problem the new mask has a speech diaphragm and the exhaust is mounted very low in the mask so not much room.
After a couple of failed experiments I ended working this design out in Tinkercad 
The red part fits in the mask and the other bit holds the HEPA filter in place. I've since added the vent in the top in case the filter is blocked off by the chin guard but I don't think it will be.
All that remains is to keep printing out batches of the exhaust covers and hope that the meagre amount of filament holds out till were done.
That's all for today Hivers another print is ready to come off the bed.