For just one, do not use the label feature at all.
Create and use the shape you want under Insert Shape.
You can have rounded corners, ovals and some fairly weird shapes.
You can double-click on those and add text.
You can give a picture fill, etc.


Position it on the page to print properly with your printer.


Otherwise, if using labels, you are stuck with rectangles because labels are tables and table cells are always rectangles.


You can, if you want, put a shape inside the label, just as you can any graphic.
Graphics on labels by Graham Mayor, MVP