Okay, technically she's not a Vocaloid in and of herself, but her design is so bad-ass I had to draw her: Black Rock Shooter.
She makes a fun contrast to the other cards. Their backdrops were all abstract light, shapes, and bright color filters, whereas B*RS here is all hard edges, rusted metal, and splatter brushes. Super fun to do.
Anywho, here's the rest of the series. This one will wrap it up for now, just in time for Otakon!
Len & Rin [link]
Hatsune Miku [link]
Luka Megurine [link]
SF-A2 Miki [link]