Here is an air tight DIY filtration mask and near air tight face shield using a cottage cheese container and a 2 liter pop bottle.
On the shield I used 1-1/4″ wide by 1/4″ thick foam peal-and-stick weather seal, but you can use something similar to protect your face from the plastic shield.
For the air inlet a series of small holes were drilled. Each hole had to be deburred with a pen knife. To protect your face, three layers of vinyl tape cover the top edge.
Two rubber bands hold the mask to the face.
A 3-1/2″ length of plastic coated solid copper electrical wire was laid over the nose bridge and double taped in to place. Two rubber bands hold the two layered 1/4 sections of Scott towels for the filter, then the edges were trimmed. Scott Shop towels are not the best as these are made of wood pulp.
The ZEP and TOOL BOX blue towels are a poly fiber product and in one thorough test proved to be pretty decent in filtering very small particulates. They also found the Scott Pro shop towels, although of the same material, did not prove as good at filtering as the ones for mentioned.
In the same tests the HEPA vacuum bags, which have a very good filtration rating, proved difficult to breath through.
Here I’ve laid my mask over another 2 liter bottle. I came up with the shape by looking in a mirror to match the mask nose bridge profile.
I use one rubber band to secure the shield to my face.
Here are the tools I used to make the mask and shield. The candle was used to heat up and bend a nose ridge. My video goes into detail of how I made these items.
Below is a template for the face shield. You may be able to print it out, cut it out with scissors and transfer the pattern by placing the top edge two inches from the bottle bottom neck. Tape the template in place then trace around the edges with a thin felt pen. Cut out with scissors. Drill two holes for the rubber band and add your foam around the top edge and sides. Take a better look at the second image to get a better idea of how I I did this.