Got an oval cookie cutter? I've been sifting through my kids playdough stuff for round and oval cutters to use. Also, feel free to downoad the image I posted of the 5 little greeblie things on the helmet. I revised a couple of them to look right. My oval maybe a bit thin, but that's why I was suggesting the playdough or cookie cutter. Hobby Lobby has sets of oval shapes for clay molding, but I think cast off play dough ones will work fine for me.
If those suggestions aren't useable, then may I suggest wetting your fingers and smoothing out the edges? They're just a bit bumpy. The symbols are fine as far as I can tell.