Agrippa was the first to publish on the usage of Kameas, or Magical Squares, to derive Planetary and Angelic Sigils. Why use sigils? Think of sigils as the personal phone numbers for the Angels and Spirits of Intelligence you wish to connect with you when performing planetary-specific magical work.

KAMEA OF LUNA (in Hebrew)
For Theoricus, we will examine how to create a sigil using the Kamea of Luna. Compare the above Kamea of Luna, transliterated from the assigned Hebrew letters into each letter’s Gematria value. Below is how the Seal of Luna is derived using the Kamea of Luna.

Seal of Luna
Going further, kamea sigils can also vary by language. I normally transliterate to Hebrew, which is Agrippa’s method, but magicians also report success with kamea sigils derived from English. Sometimes that can be a better way to go than trying to puzzle out the Hebrew spelling of an English name. In order to employ that method, you number the English letters thus:
The caveat with using Hebrew versus English: do not mix languages. Either transliterate your sigils using Hebrew-only, or English-only.
To create your sigil for, say, Gabriel, you need to know the proper Kamea to use. In this case, the kamea sigil for Gabriel, the angel of the Moon, can be created from the Kamea of Luna, as pictured below.
Basically, the name is the word corresponding to the angel, and the sigil is the shape. Or, more to the point, one shape out of several possibilities. The process is simple. First, properly spell GABRIEL in Hebrew. Next, map each Hebrew letter, as transliterated into Gematria, onto the Kamea. Beginning letters are denoted by a Circle. When you arrive at the last letter of the name, you draw a small Bar to “end” the sigil.
You now have yet another reason why you must memorize the various Archangelic, Angelic and Spirits of Intelligence for each of the seven planets. You do not want to utilize the wrong Kamea when generating your sigils!