Tape a sheet of paper to the outer face of the Monocoat and cut on the lines.
There are so many folks out there with vinyl cutters that generally, when I cut out letters by hand it's because I want a "done by hand" look to it. So I just draft what I want with a Sharpie marker on the 'coat, then start whacking away. Usually the shape of the letters changes as I go, because the whole point is to have fun cutting out letters.
If I want perfection, I make a cut file and start kissing up to someone with a cutter.