The original Raven Triskele was carved in whalebone. It is quite 3-dimensional at 4cm tall (1.5″) and has a nice weight of ~ 16grams in sterling silver.
When you see a crow or raven there are always 2, but when you see three together it is a representation of a family unit. A raven offspring will live with its parents for a number years until it finds a mate and will mate for life.
Ravens are very ingrained in all world myths. Note the egg and shell shape symbolizing life itself. The Triskele pattern of three represents good luck and eternity in Celtic art.