User Guide

Assembly FAQ

Q. What filters are recommended?

A. We have completed pre-NIOSH testing of the BE mask using a polypropylene filter material with a MERV rating of 15. It is important to use filter material made from polypropylene plastic that does not contain hazardous materials like fiberglass. On the MERV rating system, level 15 includes an efficiency above 95% with particles as small as 0.3 microns for air filtration systems. While the material passes ASTM standards for differential pressure, NIOSH testing involving masks using the filter have not been completed. The filter material is not a replacement for an N95 mask, but our testing indicates it works much better than a bandana. For more information on our materials, please review our Biocompatibility Assessment and Materials within our Testing and Validation. As always, check the material safety data sheet for any material used as a filter.

Q. Where can I order filter replacements? 

A. We have been purchasing sheets of the filter material we tested from the supplier McMaster-Carr. Each sheet can be cut into about 2500 single-ply 2.5” squares. Our tests included single and double layered filter materials. If you use 2-ply filter inserts, one sheet will support 1250 filter inserts. If you find other suppliers or materials that better suit your needs, please tell us about them on the BE Hub space! Follow our testing page for filter material updates.

Q. What do I do after assembling my mask?

A. Wear it and share it!  Protect yourself and your community! Take care of your BE Mask using recommended sanitization practices. Share photos on our Instagram account @BEmask_PPE.  You can also create an account in our BE Hub space to share photos, provide feedback, and follow our latest developments. Follow our support for local and global community movements.

The BE mask is offered to the general public for general, non-medical purposes. In accord with FDA Emergency Use Authorization, it has been submitted for review to NIOSH. The safety and efficacy of any mask depends on fitting, sanitization practices, and filter materials. Any mask should be tested and fit to meet local needs and standards. Please see our user liability disclaimer for details.

Materials Needed

  • 3D printed parts (mask body and filter frame)
  • Filter material (see details above, under Description of Mask Components)
  • Gasket material (see details above, under Description of Mask Components) – this is optional for masks printed in TPU. Skip to our video guide for installing the gasket lining on the mask below.
  • Strapping material (see details above, under Description of Mask Components). The instructions below assume ¼” elastic.
  • Barrel locks (optional, see details above, under Description of Mask Components)


Mask Prep

  1. If the mask body is printed in TPU, there may be some hair-like strings and other minor imperfections inside the printed part as a result of travel moves. These can be easily cleaned up using a blade and/or a heat gun. A rotary tool with a nylon brush attachment is also very useful for smoothing out the inner edges of the mask where it touches the face. Skip to the Be Mask Fabrication Guide for details.
  2. If the mask is printed in PLA (not recommended for version 1.3 and later), you can achieve a more customized fit by thermoforming the mask to your face. To thermoform the mask, boil a pot of water. Once water is boiling, remove from the burner. Holding the filter end of the mask, dip the edges of the mask in the water for 15 seconds. Slowly place the mask on your face (make sure it’s not too hot) and use your free hand to help form the edges of the mask to the contours of your face. Start by squeezing around the nose portion. Then, hold your free hand over the filter opening and suck in air to pull the mask tight on your cheeks and chin. You can repeat this process to achieve a satisfactory fit. You can use your free hand to help the forming around the chin area. If you are successful you should feel less air leaking around the edges of the mask when you hold your hand over the filter end and breathe in-and-out.

Filter Assembly

  1. Cut two 2.5” square pieces of the filter material and insert them over the filter compartment on the inside of the mask body.
  2. Align the filter frame so that the two angled corners are at the top of the mask body, by where the nose would go.
  3. With the filter material centered over the filter area, press the filter frame into the mask body as far as it will go. Ensure the filter material is well centered so the entire opening is covered without any gaps.

Strapping Assembly

  1. Cut a piece of ¼” material about 42 inches long.
  2. Run the elastic through the strap connectors on the mask body as shown in the photo below:

Install the Gasket Material 

(optional for TPU mask prints, but strongly recommended for PLA or other rigid materials). 

  1. Cut a piece of c-channel gasket material (the length varies based on the mask size – a large mask will need about 15 inches of gasket material).
  2. Line the outer edge of the mask with the gasket material, starting at the center of the bottom edge of the mask. The two ends of the gasket material should meet up at the bottom.
  3. Secure the gasket material to the mask body using super glue. Do this part in stages. You likely will not need to use glue around the entire mask perimeter. We recommend focusing use of glue where the gasket ends meet and at the sharp contours of the mask.
  4. Skip to the video tutorial for this step below.

Guide Videos

BE Mask Fabrication Guide

Gasket Video Guide