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You can buy this paint from a craft store. It is different from silver spray paint in that it has a reflective, mirror-like finish. Some brands call it "looking glass spray." A vase or mason jar would work the best, but you can use other items too, like a glass lamp shade. Spray the item with glass cleaner, then wipe it down with a lint-free cloth. Be sure to clean both the inside and outside of the item. If you plan on painting the inside of the item, cover the outside with masking tape. If you will be painting the outside of the item, then stuff the item with newspaper. Painting the inside will give you a nicer finish, but you won't be able to use it as a vase. Painting the outside will leave some texture, but you'll be able to use it as a vase. Choose a spray bottle that has a mist setting--do not use the kind with a jet stream. Fill the bottle halfway with white vinegar and the rest of the way with water. Close the bottle, then shake it up to mix the solution inside. Go outside or into a well-ventilated room. Shake the can of spray paint, then hold it 10 to 12 inches (25 to 30 cm) away from the glass item. Apply a light, even coat of spray paint using a sweeping, side-to-side motion.  Some people like to spray the glass with the vinegar-water first, let it dry for 1 minute, then apply the paint.  The paint will look cloudy when you first apply it, but it will eventually turn more reflective. Apply a light, even coating of your vinegar-water solution to the item. Use enough vinegar-water to bead the glass, but not so much that it starts to drip. You should do this even if you applied the vinegar-water before the paint. Crumple up a paper towel, then press it against the wet glass. The paper will pick up the excess water and paint, and leave behind a crinkled texture. Press lightly to remove less paint, and firmly to remove more paint.  Don't rub the paper towel across the glass or you will get streaks. To make the mottling effect more controlled, dampen the paper towel with the vinegar-water first. Mirror-finish paint is very thin, so 1 coat may not be enough to get the coverage you want. If the glass is too translucent for you, simply spray the glass with more mirror-finish paint, mist it with vinegar-water, then blot it. Plan on doing 2 to 3 more coats of paint. For a more distressed look, apply a coat of flat, black paint to the inside of the item, then blot it with a crumpled up paper towel. Let the paint dry for 10 minutes, then apply a final misting of mirror-finish spray paint. Do not spray it with vinegar-water or blot it. This will help give you a smoother finish. Most spray paint takes 15 to 20 minutes to dry to the touch, but it can take longer if you live in a cold or humid area. Once the paint has dried completely, remove any newspaper or masking tape. Display the item as desired.  Some paints have a curing time of several days. Check the label to be sure. If you painted the outside of the vase or jar, you can fill it with water and use it as a vase for fresh flowers.

Summary:
Get a can of mirror-finish spray paint. Clean your glass item with glass cleaner and a lint-free cloth. Mask off the side of the item that you won't be painting. Fill a spray bottle with water and white vinegar. Apply a light coat of mirror-finish paint in a well-ventilated area. Let the paint dry for 2 minutes, then spray it with the vinegar-water. Blot the glass with a wadded up paper towel. Repeat the process to get the look you want. Apply a final coat of paint if you want a smoother finish. Wait for the paint to dry before using the glass item.