This is a 'teaching pattern'. This pattern teaches you how to make a properly fitted mask. Since every face is a little bit different, this pattern also shows you how to measure and adjust masks to fit properly. Using dolls.
Pattern also includes handy links to human-sized resources at the end like studies on fabric filtration efficiencies, in case you happen to be interested in applying the skills you learned from playing with dolls elsewhere ;)
You also don't have to go through checkout to get this pattern! You can download it directly from the blog, here: https://www.requiemart.com/blogs/news/free-pattern-dolly-face-masks