You could make this. I would strongly recommend you do this out of isomalt and not just straight sugar. If you oil the cookie cutter, it should pop right out. The two big problems are that what ever you pour it onto needs to be incredibly smooth and if you heat it too much, it could be slightly yellow. You could actually make it more narrow than the one made out of plastic shown in your picture. However, if you do that then you need to think about how it is going to balance on the cake.
You would cook the isomalt crystals with a few drops of water until it is the proper temperature. Remove from heat and let it cool about 5-10 degrees. Then pour into the mold. Let set up until it is almost cool and pop out. Done. Paint at will. It is only going to last a few days. Longer if you cover it with an edible lacquer. However, it will not last a week regardless of what you do it. Do not refrigerate under any circumstances unless you are looking to destroy it quickly.