[btbuildem]

I share the common setiment from the comments: the avatars are hard to tell apart, which means they fail in their purpose as quick visual identifiers.

I've dabbled with this in the past, what I found very helpful was symmetry -- this works especially well with abstract shape ones. Generate a piece, then mirror it horizontally (or vertically, or both). I found this kind of visual redundancy made the glyphs more attractive to look at, and more distinct / easier to tell apart.