I am working on designs for a yoyo and thought of this question.
Nipple would be like the Turning Point Leviathan
Nipple Spike = Radical Seas Set Sail
Spike = Monkeyfinger Caeser
Convex = TP Shake or YYF Dogma
Concave = YYF Horizon or iYoyo
Flat = YYF CZM8