hey jolie, i have made lots of masks, so here is my take on the process......i always use thin veg tanned leather...1mm..i think this is 2 or 3oz for you. I soak the piece of leather in warm water until the bubbles stop rising...this is about 1 or 2 minutes. For a full face, the nose is going to be the hardest part, so what i do is grab the leather in two hands and vigorously work the leather up and down...hands going in opposite directions. I do this for a good 5 minutes, moving my hands around the edges, so the leather is worked and stretched in all directions. What this is doing is breaking up the fibers in the leather is it will be easier to work. You will need to stretch the leather where the nose will be...so grab something that is small and rounded at the end..(round end of knitting needle...end of spoon) and push from the back until the leather stretches into a good size bump. Dont worry is it looks strange because you will need the excess of the bump to press down over the nose. Now place on the face mold that you are going to use and start pressing down with you fingers. I find fingers work great at first and then maybe go the modeling tool to finish. I use sewing pins with the balls on the end to hold the leather in place while it dries. Place the pins away from the face otherwise you will get holes in the leather that will be seen. When the leather dries it will hold its shape. I think i may have a go at this today and will post some pics of what i come up with. The pics below show the modeling head i use and a pic of a full face mask that i have made.
hope this helps.
cheers
caroline