Hard Shell Basic Mask

Update
31/03/2020 (2)
I have uploaded a few new picts of the latest design.

I do not recommend printing the bottom section (part with threads) in TPU as the threads will tend to bind more readily than with PLA to PLA. It may work fine if the whole section can be printed in TPU but if its just the end, the TPU and PLA may separate under the pressure of threading in the filter. The TPU gasket is loose at the threads so this doesn't have the same issue. It could also be an issue of my print being done quickly and at a low resolution.

So far my silicone sealant gluing appears to be working okay. I tried using a cyanoacrylate based glue which works but is rigid. After the materials flex for some time the bond weakens. I am hoping the flexible silicone sealant won't have this issue.

31/03/2020
I have added a new version of the PLA/TPU combo mask (V3) The new design fits my wife and me pretty well.
It does need to be shifted on the face to allow it to seal properly.
I left off