DB's Basic Respirator with replaceable filter

This is a simple and strong mask with replaceable filter.

Total print time on a common printer should be less than 8 hours.
Shell thicknesses of 6 top/bot and 4 perimeter with Infill set at 30%

I've used layers of cotton and carbon filter discs for the filters.
This will accommodate the standard disc filter cartridges with 35mm thread.

Superglue the Nose part into the Body of the mask.
I sealed the interior walls with clear lacquer.

The hooks should be attached with superglue or epoxy,
1/4" or more from the edge to prevent strap irritating checks.

To get a good seal, glue a liner of flexible rubber or foam
along the inside edge and edge. If you use silicone rubber,
let it cure fully otherwise you'll get a skin rash from it.