How do I create shot glasses made of ice ?
Fill a 3 oz plastic cup to 2/3 then place the 1 oz cup inside the 3 oz  cup and push it down until it is about level with the rim of the larger cup. Add a stone in the 1 oz cup to help to weigh it down without sinking. Stabilize the 1 oz cup in the middle with duct tape over the 2 cups. Place inside the freezer 6-8 hours.