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BK,BK!, BK! avatars, BK! icons, BK! pixel art, BK! forum avatars, BK! AOL Buddy Icons
>making the "BK!" square 3d.
Rotate cube a bit and draw one of sides of cube with lighter grey than another.
You dithered too much so cube and letters are hard to read (don't dither - and it will stand out on dithered background). Also letter 'K' looks unfinished (vertical 'holes' are too short). Exclamation mark is 3 times thinner than the rest of letters (it should be as wide as "I" part of 'B').
And for proper avatar better substance needed - see how graffiti writers add stars, bubbles and characters to their pieces.