Looking good adam your helmet is alot more acurate now, the smoothing out shoulnd't be too hard, get some thing steel guitar string to cut away any unnesecary high spots and use a butter knife's non serated edge to do some smoothing and use a smothing agent, I know its not water based clay but like water would smooth that kind of clay, i don't know if you have tryed anything yet but if it is oil based paint thinner might work with a soft brush, but i would do a test on a piece that isn't part of your helmet first. Kepp up the good work!