inspired by one of the inventors of identity-based encryption, professor matt franklin. identity-based encryption keys are derived from an email address, "x at y dot z".
an atdot is the boolean intersection of a sphere and an @ sign extruded along the z axis.
from one angle an atdot is an 'at', @, and from another it's a 'dot', •.
YMMV. the printed part is 1500% scaled up from the model. mine was oriented with the @ sign reading correctly viewed from the front (the "window" of the ultimaker).
support removal is difficult if you dont have soluble support.
i accidentally broke my atdot while removing support, and had to glue it back together. the silver lining was that it was easier to remove the rest of the support with the outer shell separated from the inner shape.