When I make masks I'll use put them in a square or rectangular area, that way when cut out I can tell where they should line up ? Is that what you meant OneKiwi ?
The vinyl I use is 200mm x 50m, so I just cut what I need off the roll, up to 1 metre long and feed that through the cutter. As for putting it on, I just use the same masking vinyl, it's clear, you can see through it, there are always off cuts lying about to use. And you can use it a couple of times if you're as tight as me