Here are some early mockups and one of the first prototypes:

The first prototype had uneven eyes

Why a hummingbird?

Early on, a hummingbird image was created for the Dart team
to use for presentations and the web.
The hummingbird represents that Dart is a speedy language.

However, hummingbirds are pointed and angular
and we wanted a cuddly plushy, so we chose a round
hummingbird.

Shams specified which color would go where,
the tail shape, the tuft of hair, the eyes…all the
little details. The vendor sent the specs to two
manufacturers who returned the prototypes some weeks later.

Introducing Dash at the January 2018 Dart Conference: