Nero will probably jump in here with an answer as it pertains to his thread-head . . .
You can find the traditional sigils of the Elemental Kings (et al) in many books on ceremonial magick. Or, you can take the Rose Cross, and play connect the dots using the name of the spirit. Done correctly, you should end up with the same traditional sigil you might find in many books on ceremonial magick.
THIS site has a basic introduction to this method. It ends with a note about the potential difference between sigil created through the English verses Herbew alphabets . . . this is to be considered when comparing your sigils to traditional ones.