People of all shapes can cosplay. I just saw a hexagon in a Hatsune Miku cosplay last week.
Anyway, glad to hear you've decided to start cosplaying. The people here are wicked helpful and love to give advice from experience, so don't feel shy about asking questions.
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Want to help create a US anime convention map?
PM me your local conventions to add to the map
COSPLAYS IN PROGRESS
Soren (Fire Emblem Radiant Dawn) - 4%
Vaati (LoZ Minish Cap) - 2%