If you're entertaining a large group of people and want each of your guests to have access to their own shot glasses, it could be costly. Instead, use items you have on hand to make shot glasses that will have your guests talking.
Fill the larger paper cup with about 1 inch of water. Set the smaller cup or paper cone inside the larger paper cup.
Press the smaller cup or paper cone into the water in the first cup, leaving about 1/4 inch to 1/2 inch of water at the bottom of the larger cup (don't force the smaller cup all the way to the bottom of the larger cup). Add more water to the large cup to fill it to the brim.
Place a strip of tape over the smaller cup or paper cone, wrapping the tape onto the larger cup to hold them into place.
Place the cups into the freezer on a flat, sturdy surface. Allow the water to freeze completely (several hours).
Remove the cups from the freezer. Peel away the outer paper cup. Remove the smaller paper cup or cone. Run a small amount of warm water inside the inner cup to loosen it, if necessary. Store the shot glasses in the freezer.
Add food coloring to the water for shot glasses that coordinate with the theme.
Don't take the shot glasses out of the freezer until you're ready to use them, or they could melt.