This is a reusable mug that twists and telescopes from a collapsed, compact configuration to a full-size cup.  In its compact form, it is small enough to fit in a pocket for easy carrying.  In its telescoped and locked configuration, it has rigid insulating walls for grasping comfort and silicone o-rings to ensure a leak-proof seal.  The twisting mechanism ensures that the cup does not collapse catastrophically when it is in use.  The cup will be made from post-consumer polypropylene, which is recyclable.  Every 100 refills, a customer earns a new "badge" that can be attached to the mug, so they can show off their commitment to reusable cups.

A video of the working prototype can be found by visiting this site:  http://web.mit.edu/msiboni/www/MilleMug/Use.html

Thank you very much!