Not to revive a thread but I'm new here. When I started doing mask covers, I went super simple. I brought a mask home and took a sheet of velum paper, taped it on and rubbed a pencil around the edge lightly which highlighted the ring edge that secures the visor. I transposed that to a piece of thinner piece of cardboard (like the kind you find a beer case made of) with a stylet, cut it out and labeled it for that mask (ie. MSA G1) and it resides as a template on my desk. Hope this helps.