They have lots of the large ponytail ties in the picture at the grocery misc hair isle as of 3-29-2020- They come 24 in a package so -12 masks per package... I got 4... so I am going back today with masks donation to them and get some more.
Here is the link for Youtube video instruction and pdf pattern for this style filtered mask... you can use ponytail ties or read microbiologist notation under the video
nurse video <---link
PDF PATTERN FOR THIS MASK <----link
Notation from microbiologist under the video- his suggestions