What is the easiest way of doing that? I already know how to make interactive diagrams, I just need to know how to use custom pieces images
To use a custom image (i.e. an image not present in the directory where the other pieces are), you must upload the image, and use the URL of its location in the HTML description of the Diagram, with the color prefix replaced by a % sign.
IDK but my new chess piece is...
Warship!
Reskin of queen, like how the boat is a reskin of the rook
Raft!
Reskin of pawn
Cargo Ship!
Reskin of king
Scout Ship!
Reskin of horse
Submarine!
Reskin of bishop