DIY 3M like masc foldable

Final version of my 3M like masc foldable. I have designed it to be as efficient as a 3M masc. 21 prototypes have been made and tested them in real situation to optimise every part of it.

All you need are elastics and scissors to adapt it to your face.

Tests:
- safety coefficient, to improve some areas resistance
- clips resistance
- mounting test (balance between fixation resistance and flexibility)
Validation:
- I have worn it 3 days 2h/day.

Be very carefull the first time you fold it and follow global steps:
- 1: fold the bottom (slowly)
- 2: fold the top parts (easy)
- 3: fold verticaly in 2 parts (slowly)
- 4: fix the nose like on pictures (it is not easy, fold the nose in 2 part make it easier)
- 5: adjust the masc to your face (the top part are very flexible)

Well fixed, this masc is very resistant.

The model size is big, you can reduce it by 10% maximum with Cura.
I will update the STL for smaller versions if requested.

I strongly recommand to fil