3/21/2020 Update:

Mk2 is released:
https://www.thingiverse.com/thing:4234928

Mk2 has an increased filtration area of ~60%, making the user easier to breathe. For Mk2, one surgical mask can be made into 6 filter disks.

3/21/2020 更新：

发布Mk2型号：
https://www.thingiverse.com/thing:4234928

Mk2增大了~60%的过滤面积，使用户更容易呼吸。使用Mk2时，一个口罩可以被裁剪成6个滤片。

3M Respirator Surgical Mask Adaptor for 3M 6xxx/7xxx Mk1

To make two full assemblies for one 3M respirator, you will need to print two copies of each following models: <3M Mask Adaptor_Spacer_垫片.stl>, <3M Mask Adaptor_Shroud_滤盒盖.stl>, <3M Mask Adaptor_Adaptor_滤盒转接头.stl>.

Each conventional surgical mask can be cut into 10 to 12 filter "disks", effectively increasing each mask's life span by 5-6 times. Inlet of the filter shroud diverts airflow 45 degrees towards the user's face, further lowering the chance of contact by aerosol coming from the front side. External surface of the filter can can be disinfected by directly spraying 70% ethanol/isopropanol without damaging the hydrophobic property of the mask. The size and shape of the filter can have been optimized for ease-of-use and aesthetic purposes.

Part <3M Mask Adaptor_Adaptor_滤盒转接头.stl> was adopted from lucifer01's design: https://www.thingiverse.com/thing:4147665

If you do not have direct access to a 3D printer, you can try these following commercial 3D printing services:
For China Mainland: www.mohou.com
For the United States: www.shapeways.com

3M 6xxx/7xxx系列呼吸面罩至外科口罩转接头 Mk1

一个呼吸面罩搭配两个组装完成的滤盒使用，需要打印以下模型每个两份：<3M Mask Adaptor_Spacer_垫片.stl>, <3M Mask Adaptor_Shroud_滤盒盖.stl>, <3M Mask Adaptor_Adaptor_滤盒转接头.stl>。

每个标准外科口罩可以被裁剪成10到12个滤片，可以有效延长每个口罩的使用寿命5至6倍。滤盒的进气口被设计为45度角偏向使用者，可以更有效防止正面的气溶胶接触。滤盒的外部可以直接喷上70%酒精或异丙醇擦拭消毒，不会影响外科口罩滤片表面的疏水性能。滤盒的大小以及形状经过优化设计，考虑到了美观和使用的方便性。

<3M Mask Adaptor_Adaptor_滤盒转接头.stl>使用了lucifer01的设计：https://www.thingiverse.com/thing:4147665

如果您没有3D打印资源，可以尝试以下的商用3D打印服务：
中国大陆： www.mohou.com
美国： www.shapeways.com

Printing Instruction:
打印说明：

3M_Mask_Adaptor_MaskCutter_口罩裁剪模具.stl x1

This mask cutter helps you to make filter disks, print it with any layer height or material.
这个口罩裁剪模具用来帮助裁剪正确尺寸的滤片，任何层高或者材料均可。

3M Mask Adaptor_Spacer_垫片.stl x2
3M Mask Adaptor_Shroud_滤盒盖.stl x2
3M Mask Adaptor_Adaptor_滤盒转接头.stl x2

Please use at most 0.1mm layer height, PLA or PETG filament, and >80-100% infill to ensure a tight fit of the assembly. Print one part at a time to minimize the chance of stringing.
请使用小于0.1mm的层高， PLA或PETG塑料，以及大于80%至100%的填充打印以保证气密性。逐个打印每个零件，避免零件间的拉丝。

Disclaimer: By CC BY-NC 4.0, you may not use this design for commercial purposes. When assembled and worn correctly, this design may only provide the same or lower protection level your material of choice may offer you. The efficacy of this design has not yet been tested to warrant protection against airborne diseases. This design has not been reviewed or approved by any health professional or official, please use it at your own risk. The choice to use this design for any particular intended use is the sole and exclusive responsibility of the user; and I shall in no event ever have any responsibility for, nor incur any liability for any particular use or application of this design. For your safety, avoid high-risk contact as much as possible.

根据Creative Commons CC BY-NC 4.0许可，请勿将此设计用于任何商业用途，例如售卖此设计或售卖此设计的打印成品。当安装和佩戴正确时，此设计只可以提供与滤片材料相同或更低的防护等级。该设计并未经过实验验证防止空气传播的有效性，亦未经任何医学专家或权威的评估和许可，使用所带来的风险请自行承担。为了您的个人安全，请尽量避免高风险接触。