For people who have a wide toe nail, i have used 2 peices of minx -and layered as Geeg says.
However....if you use the silver/golden lightening ones - the plain metallics, if you are not careful, you can see where one overlays ontop of the other. So to rectify this, i apply the largest minx peice and use that, tailored to fit perfectly to the outside edge of the nail sidewall on the outside edge of the big toe, then, to apply the smaller peice to go down the inner side wall of the big toe, I offer it up to the partially covered big toe & rub it over it, which will give you the line to cut (the already applied minx edge will be raised, therefore creating a higher plane for you to rub and get the 'line') Then, carefully cut the thinner minx to fit.
I have always kept all my old unused Minx pieces just for this purpose.
Hth's xx