A can of KRYLON looking glass mirror like paint.( they don't have this at Micheal's. I found mine at wal mart, or they have it at Hobby Lobby)
Also you will need a spray bottle filled with a 50/50 mixture of vinegar and water, a paper towel, and painters tape.( something to cover the outside of the glass while painting)
After covering the outside of the glass ,spray the INSIDE of your glass... 1 coat at a time, allowing each coat to dry about 1 minute before starting the next. It will take about 5 coats, and will look like this when its done.
Allow to dry for about a minute. Then using your vinegar/water mix spray into the glass. It will bead up like this.
Let that sit for about 30 sec. to 1 min. Then fold a paper towel in to a small square and dampen that with the vinegar water mix. Trying not to bump the sides of the glass with your hand, begin to lightly dab the towel against the glass. You will see the paint starting to rub off.
Keep going until you have your desired look. I would dab a little, then look to see if it was what I wanted.. After I was done I took the spray paint and did one more light coat.
and WAAA LAAA