I'm not sure exactly what you mean when you say you can't get the eyeholes to match on the pattern. Are you talking shape? Placing? Either of those can only be fixed with practice and redrawing until you get something that works.

For formed leather masks you can also make a blank of clay-- use the #4 Roma Plastilina-- it is very stiff-- so be patient with it. Then FREEZE it, stretch the leather and burnish it-- you will only get one mask out of this blank. Less sculptural masks can be achieved by cutting a mask shape out of veg tan leather and wetting it-- then folding and twisting and pinching the edges to the form you want. You need to wait until the leather is not sopping wet and not completely dry-- some experimenting with a scrap will show you when the magic moment is. This method does not give you a ton of time to work on the piece, if you MUST you can rewet the leather a light mist on the suede side works best for this. Beware though, you risk marking the with water marks which will show depending on how you finsh the mask and undoing some bits that you have the way you want them. Hope this is helpful!