These dollar store vases are beautiful cobalt glass that were fine as they were but I can never leave well enough alone. Stained glass artists' copper tape is great for trim but it is too narrow to work in any of my border punches. It is also nice to have a blue/silver scheme. An elaborate pattern in copper can be a little overwhelming.
These are the supplies you will need: Foil duct tape, a border punch with a pattern narrower than the tape, a craft knife, a burnisher of some sort (a smooth, rounded wooden tool handle works well), a pair of sharp scissors, isopropyl alcohol or other residue-free glass cleaner. I used a paper cutter to divide the tape lengthwise. If your design uses the whole width of the tape or cuts both edges, you will not need this. You could also cut by hand with a craft knife and ruler but it is kind of slippery and delicate, so I find it challenging. You will also need a vase. Straight sides are a lot easier than curved shapes.
An unaltered vase in action.
As you can see, this tape is $5.99 at the hardware store. I bought it to make embossed gift tags for Christmas presents and had plenty left over to play with. (Ulterior motive? Me?) There are many names for it: HVAC tape, foil duct tape, metal repair tape, aluminum foil tape. It is not the fabric duct tape that ingenious people use for wallets, purses, costumes and car repairs. It is very thin, springy aluminum with a paper backing. It is easily kinked and bent, so the flatter you can keep it, the more you will thank yourself.
The first step is to measure the circumference of your vase and cut a piece of tape with a little extra. Squaring the ends is a good idea. Measure the length of the pattern of the punch and divide the vase circumference by this; if you want it to match at the seam, the result must be a natural number. There is a tiny bit of stretch in it, but not much. Even though these vases are mass-produced, there is enough difference that one has a continuous pattern and the other is mismatched by 1/4" or so.
Punch the border design. The best results usually come from starting with the pattern centered at the midpoint of the foil and moving the tape to each side. I punched both sides before cutting it into two strips because it is easier to handle a wider tape.
A bonus: depending on the pattern of your punch, the cutouts can be great for other projects. Mine produced lots of little fleurs de lis which are perfect for cards, votives and many other things that desperately need fleurs de lis.
Another bonus: cutting foil is a method of sharpening punch dies. Before putting it away, put some waxed paper sheets through your punch and, where possible, lubricate the mechanism with a silicone grease or whatever the manufacturer recommends. Then feel virtuous for caring for your tools.
If you are halving the tape lengthwise, do that.
There are several ways to get an even line around the vessel. One is to secure a pen to a platform so that the tip is at the height where the straight edge should be, then rotate the vessel against the pen. For translucent vessels, you can also cut a band of graph or lined paper with a very even bottom edge and tape it inside, with that edge flush against the bottom. A flashlight inside can help you see the lines through colored glass. Whatever method you use, clean the glass first. It will help the tape to adhere.
Tip: When removing the backing, hold the metal taut while peeling off the paper, not the other way around. This will help to keep the foil smooth.
Starting with the center on a seam (if your vase has one), follow the line around each side to the other seam. The adhesive is very sticky and the tape creases easily, so try to handle it as lightly and as little as possible. Burnish the tape down smoothly, beginning at the middle and going toward the ends. Aluminum is pretty soft, so the rounded wooden handle of the burnisher produced a better surface than the steel. The back of a spoon also works.
Wipe down again, add flowers, and you are done! Enjoy your work!