I don't use needle files for nut making so they are not absolutely required. My nuts are shaped with small, but larger than neddle files from Stew-Mac - this is the rough shaping. Next they are sanded with various grits to final size - a small surface plate with sandpaper taped on it works great for this.
For the string slots I start with a razor saw to score the desired string location and then go at it with nut files. For the high E I start with the proper nut file and for the larger strings I start with a smaller nut file to get the cut going and then switch so the size nut file that the particular string will need.
But no needle files in my process at all.
