The idea behind using plaster is because it is easily carved and shaped it is also easy enough to make a cast of, the reason i need to make a cast of it is because it is to brittle to use as a functional last. This was my first attempt using plaster and in my opinion it turned out quite good, I began be making a wooden box to fill with the plaster, let it set and then drew the basic shape of a foot from both sides and from above onto the block of plaster. I then started to cut chunks off to refine it down to what it looks like in the 2nd and 3rd image.
I then used a sort of cheese grater tool to get the final shape i wanted. The 5th image will be the exact shape of the upper of any shoe that i use this last for.