COVID-19: Make Your Own Mask [Updated 4-28-2020; See Below]
Goal: with the nationwide PPE shortage, lots of time on my hands, and a couple of printers in the basement... I had no excuse but to get to work! Thankfully, by building on the work of a friend and several open-source designs that were already available online, I think that we were able to achieve satisfactory results in record time. Many thanks to all of the people that helped me along the way, and to my parents who helped me to assemble a bunch of these at home!
This mask, unlike many alternatives, features an easily adjustable elastic strap. More importantly, the semi-rigid frame ensures a tighter seal against your face than something like a surgical mask could provide, which means that more air goes through the filter as opposed to around it.
I'm sharing the files below, for free and with no expectations other than that they'll be put to good and fair use -- and of course with the disclaimer that I am not to be held liable or responsible in any way for any problems that arise from their manufacture or use! I do not, and cannot, guarantee the effectiveness of this mask (plus, it of course depends a lot on which filter material(s) you choose to use, and how it is assembled).
Files:
Small Mask
Large Mask
Small Forming Tool
Large Forming Tool
Materials:
Process (see pictures below for visual aides):
This mask, unlike many alternatives, features an easily adjustable elastic strap. More importantly, the semi-rigid frame ensures a tighter seal against your face than something like a surgical mask could provide, which means that more air goes through the filter as opposed to around it.
I'm sharing the files below, for free and with no expectations other than that they'll be put to good and fair use -- and of course with the disclaimer that I am not to be held liable or responsible in any way for any problems that arise from their manufacture or use! I do not, and cannot, guarantee the effectiveness of this mask (plus, it of course depends a lot on which filter material(s) you choose to use, and how it is assembled).
Files:
Small Mask
Large Mask
Small Forming Tool
Large Forming Tool
Materials:
- FDM printer (any rigid material will work -- I've used ABS).
- Filter material. Lots of materials will work in a pinch, though my best results were achieved by cutting up HVAC filters rated to MERV 14-16 (comparable to N95 rating).
- Hot glue. Love this stuff... I think duct tape gets too much credit sometimes!
- X-Acto knife to trim filters with. The sharper the better; I'm using a #11 blade that is brand new and cuts like a scapel.
- 1/4" elastic. Hard to find at the moment, but can be had for a (high) price on eBay.
- Some thread and a needle to stitch elastic with.
Process (see pictures below for visual aides):
- Start by printing the forming tool(s) for whichever size mask you'd like to make (Large and Small are available... who needs Medium anyway?!). Low infill density is fine here; this tool won't be put under tremendous pressure.
- Next, print the mask itself. If possible, configure the layer settings to that there is no infill, but instead the contours themselves provide the full ~0.047" uniform thickness of the part. This helps to ensure maximum flexibility and also decreases print time -- we want to make as many of these as possible.
- Cut filter material (with knife or scissors) into squares of approximately 8" x 8" (you can cut the margins closer than this if you like, as you get the hang of the process).
- Place the square of filter material over the forming tool, and center it.
- Lay down a bead of hot glue on the inside of the mask surface, closest to the edge along which your face will rest. Ensure that the bead is continuous, and of generous thickness to ensure an airtight seal.
- Firmly press the mask over the forming tool, sandwiching the filter material in between. Maintain pressure for about 20 seconds as the hot glue cools. It shouldn't burn you assuming that you're careful, and touching only the plastic surface of the mask.
- While keeping the mask pressed against the forming tool, use your knife to trim away the excess filter material. Be very careful during this step! You shoudn't need firm pressure on the knife if it is sharp.
- Remove the finished mask and, if needed, manually trim any remaining filter material away from the edges.
- Sew a loop of an elastic band (roughly 24" long) onto the single hook of the mask.
- Loop the free end of the elastic band around the back of the mask, and down through the inner hole of the second side. Then, loop it back up and through the cinched (outer) side of the hole. Use a paperclip to help push it through the narrow section, and then grab and pull it with your hand.
Update: Roomier Fit
After making many masks and distributing several throughout our community, we realized that there was some room... err, lack of room, for improvement. It turns out that the form tool I had designed produced masks with a shallow front, which sometimes interfered the proper fit of the shell. In other words, noses are bigger than I thought they would be!
The fix, thankfully, is simple (and non-surgical!) The new forming tools and companion presses (below) work with the same mask files, but provide a roomier fabric area to better accomodate all face sizes. Leaving plenty of fabric room in the front, in addition to ensuring a proper fit with the plastic shell, also provides more surfae area for filtration, which should make for easier breathing.
Because the form tools are now so much taller, the assembly was harder to glue without creating messy streaks as hot glue dragged down the fabric. To solve this problem, I created the "companion tools" for each forming tool, which allow you you preload the fabric, compress it into its form, and keep it out of the way as you lower the freshly glued mask into position. Pictures are below to illustrate the new process -- just one extra step:
4b: Lower the companion tool over the forming tool and press firmly, sandwiching your filter material in between the forming and companion tools. Ensure that any large folds in the filter material are oriented in a way that will not prevent proper gluing to the mask frame in step 6. Leave the companion tool in place as you glue the mask to fabric; it will help to ensure that the center fabric is kept clean and free from any stray glue.
New Files:
Small Forming Tool v2
Small Forming Companion Tool (v2)
Large Forming Tool v2
Large Forming Companion Tool (v2)
The fix, thankfully, is simple (and non-surgical!) The new forming tools and companion presses (below) work with the same mask files, but provide a roomier fabric area to better accomodate all face sizes. Leaving plenty of fabric room in the front, in addition to ensuring a proper fit with the plastic shell, also provides more surfae area for filtration, which should make for easier breathing.
Because the form tools are now so much taller, the assembly was harder to glue without creating messy streaks as hot glue dragged down the fabric. To solve this problem, I created the "companion tools" for each forming tool, which allow you you preload the fabric, compress it into its form, and keep it out of the way as you lower the freshly glued mask into position. Pictures are below to illustrate the new process -- just one extra step:
4b: Lower the companion tool over the forming tool and press firmly, sandwiching your filter material in between the forming and companion tools. Ensure that any large folds in the filter material are oriented in a way that will not prevent proper gluing to the mask frame in step 6. Leave the companion tool in place as you glue the mask to fabric; it will help to ensure that the center fabric is kept clean and free from any stray glue.
New Files:
Small Forming Tool v2
Small Forming Companion Tool (v2)
Large Forming Tool v2
Large Forming Companion Tool (v2)
Update: Added Push Tool
Just one more minor update to this project! After singeing our fingertips with hot glue more than once, I came up with these handy tools to uniformly -- and without getting fingers near the hot glue -- distribute pressure over the mask/filter assembly as the hot glue cools. Hopefully they help you out!
New Files:
Small Mask Push Tool
Large Mask Push Tool
New Files:
Small Mask Push Tool
Large Mask Push Tool