Printable Barrier Mask

This is a printable breathing mask intended as a reusable barrier for shopping or being out in the world. Coupled with the right filter media this may provide some level of microbial protection, but this is not guaranteed. As it is made of hard plastic some extra steps may be necessary to get the fit right. No printable mask is better than a certified mask, though this is better than nothing. The point of this mask is to prevent contaminants from the wearer leaving the body with any speed. It is more to protect others than the person wearing it, though I think some degree of protection is afforded. I should note that I am not a doctor but have spent many years using PPE correctly in industrial settings.

My goal was to make the mask light and comfortable while minimizing the required print time. It features an adjustable headband and replaceable filter element. The safety of this mask is dependent on the filter. I use a MERV 11 furnace filter. Using my template I can get 175 pieces from a 20"x20"x1" filter which cost me $20 CAD. The elastic for the straps cost $2.50 at the local dollar store and come in 4m strips, which should fit about 10 masks.

Print instructions

When assembling masks make sure all work surfaces are cleaned and sterilized. Always use a certified mask and gloves when handling parts to be distributed. I always leave printed PPE sealed in a plastic bag with a shot of isopropyl alcohol inside for at least 3 days before distribution.

I have had good results printing in PLA and PETG. The advantage with PLA is that it can be formed by soaking the contact strip in 60°C water for several seconds then manipulate the softened plastic (take care to not get burned!!). The disadvantage to PLA is that it is biodegradable and may be more likely to harbor microbes. This mask fits my face well, I usually wear an adult M respirator.

Print all the parts
Print all the parts at 0.3mm layer height for fastest turnaround. I use 10% gyroid infill to keep weight down around the filter clamp. Choose the appropriate clamp for your elastic. Remove any plastic strings and give the mask a light sand to the contact strip to maximize comfort.

Assemble the straps
The following measurements are based on the elastic I found which has roughly a 1:2 stretch ratio. Cut one piece 22"(56cm) long for the top strap and two pieces 9"(22cm) long for the neck strap. Assemble the neck strap by inserting a 9" elastic band into one of lower holes on the mask and tie a small knot in the end to keep it from pulling out of the mask. Insert the other end of the band into one half of the clasp, see photos for correct routing. Neck straps can be tightened by simply pulling the loose ends of the elastic, and released by lifting the outer edge of the clasp away from the head. Assemble the top strap by tying one end of the long strap into the center of the Strap Tensioner ( I use a slip knot, you can also sew or staple the strap to form a loop around the tensioner). Thread the other end into one of the upper mask loops from the bottom, then through the two loops of the strap tensioner, then tie it off on the other upper mask loop like the neck loops (see pics for routing). Slide the tensioner along the band to adjust tension. Alternatively you can print a second set of clasps for the top, but I found they don't stay secured as well on the back of the head.

Prepare Filters

WARNING: DO NOT USE FILTERS CONTAINING FIBERGLASS Fiberglass particles can escape from cut edges and enter the airway causing considerable long term damage. Most HEPA filters contain fiberglass.
Sterilize all work surfaces and cut out some filter pads using the provided Filter Template. I recommend MERV 11 or 12 air filter media, contact the filter supplier for information about fiberglass content. I have transitioned to using a hot knife to cut my filter media so the edges are sealed. Always take necessary steps to avoid contamination. Make sure the groove at the bottom of the Filter Clamp is open and able to flex. This allows the clamp to be removed to replace the filter later. Place the filter pad inside the mask and secure by installing the clamp, top edge first then snap the retainers into position. Ensure the edge of the pad is visible all around the clamp or the filtration will be compromised. Double check the filter pad for holes by looking at a light through the filter, replace if necessary.

Fit the Mask
Fit the mask over the face and connect the clasp. Slide the tensioner and pull on the loose ends of the neck straps to adjust the tension for a comfortable, firm fit. Test the fit by blocking the breathing port with your palm while applying pressure and suction from you mouth. No air should escape. If you are having leakage around the seal try adjusting the straps. If the leaks persist try using hot water or a heat gun to soften the problem areas but take care not to burn yourself (i.e. use your gloved hands instead of your face). If an acceptable fit can not be achieved send me a message with a photo of the problem area I can modify the mask and release the update for all.

Mask Maintenance
Check the filter media for holes or other flaws before use. Always make sure to clean the mask frequently using 99% isopropyl alcohol or a certified disinfectant pad. Wipe the entire inside and let dry completely before wearing. Do not use your diswasher to clean or you will likely end up with a pile of goo. Store the mask and extra filter pads inside plastic bags to prevent contamination while not in use.

Etc.
As far as licencing goes, I don't mind these being sold to cover materials but please don't gouge people during an emergency. Lets all work together to keep each other safe and healthy. If anyone in the medical field has comments or requests I would love to hear them. I am located in Vancouver, BC in case anyone local has any needs.

Note
I had this mask tested by a professional respirator fitter at work today and it performed quite well considering its limitations. However, it did fail the irritant test along the chin line. So, don't count on this mask to keep you 100% safe. My estimate is that it is 90% safe. Keep washing your hands and staying away.