12 or more 6-ounce or 8-ounce glasses 12 or more pieces cellophane, 12 by 12-inches (15 by 15-inches if using 8 ounce cups) 1 to 2 cookie sheets
Place the chocolate in individual bowls and place each one over simmering water (a little lower temperature for white chocolate) to melt. Place the cookie sheet in the refrigerator. To make the molds, place the cup in the center of a piece of cellophane and bring the cellophane up the walls of the glass. Fold it over the rim, stuffing the excess inside the glass. This will make loose pleats around the glass. Adjust the cellophane so the pleats are not too tight, otherwise the chocolate may break when you try to peel the cellophane from it. Make extra molds in case you have breakage.
Hold the rim of the cello wrapped glass and dip it in the melted chocolate as deep in as you want the chocolate cup to be. Remove it from the chocolate, turn it upside down, and place it on a sheet pan in the refrigerator. Allow to chill and harden for 1 hour or more.
Remove the glasses from the refrigerator one at a time. Use a sharp scissors to trim around cellophane just below the rim. Try to avoid touching the chocolate with your fingers, as it will melt instantly. Pull the cellophane towards and against the glass to support the chocolate while you remove it from the glass. Hold the cup at the base with your left hand (if your hands are warm hold the cup with a piece of waxed paper) and with your right hand pull the cellophane down and away from the chocolate and into the center of the cup. Snip off the excess cellophane.
Place the cup back in the refrigerator for now while you trim the rest of the cups. Once they're all trimmed, remove them one at a time. Keep in a covered container to avoid condensation until ready to use. Fill with mousse, pudding, fruit, ice cream, or any cold item you desire.