This is a topic for me to post my sprites and (if I ever complete any) games in. Currently, I only have three sprites made of One Piece characters, and only one of them is completely custom.
Kaku: My first work, intended for a One Piece game that eventually failed because I got in over my head and promised to put too many characters in. It was an edit of Usopp, using Zoro for the swords. There have been complaints that his legs are too short, and I agree with those complaints.
Blackbeard: A more recent sprite. I made this shortly after the Ace vs. Blackbeard fight. It looks better than the first sprite, but now he seems too fat.
Garp: This is my most recent work, and probably my best out of the three. Shading has greatly improved, in my opinion, and I'm much more satisfied with the appearance of his face.