Not a full sleeve but it is going to cover all of my upper arm.

Wow! That’s gonna be quite something when it’s finished.

You could try here:

http://www.whats-your-sign.com/celtic-symbols-miscellaneous.html

My dad and bro both have a celtic cross with knotwork inside the cross parts and our clan crest for the circle part (we’re scottish… well our dad is, my brother and I are only half scottish).