There are a few restrictions on label size, but hardly any on shape. Just about any shape that can be drawn by hand or computer can be made into a label. The main constraint is the possible problem in removing the matrix (i.e. the unneeded material between labels) if the size and detail of a label component is very small or intricate.
Imagine, for example, a “holiday sun” image with very fine or spiky rays. Peeling off the matrix between the rays without ripping it (and leaving some behind on the liner) could be difficult. So, something to keep in mind is that a label with the matrix left in place is only suitable for hand application.
As for the size, there are limiting factors for maximum length and width, but essentially none for minimums. In theory, a label can be as long as the roll of stock it is printed on, or several thousand feet. However, the plate cylinder that prints the label image introduces a hairline gap on each rotation (every 24 inches for the largest cylinder).
Hence, a solid line or design could not be printed on the whole roll, but a repeating pattern or text message, with spaces for the tiny break, could be. There are ways to disguise the gap – it need not be a straight line, for example – and there are special laser-engraved plate cylinders available without a seam. In practical terms, though, a standard butt- or die-cut label is limited in length to 24 inches or less, because that is all the rotating cutting tool allows.
Maximum width is determined by the web size and the complexity of a label’s printed image. Full width of the Aquaflex web is 10 inches, but this could be used only if there were no requirement for registration marks, which are standard for most jobs. Accordingly, 9 1/2″ is the largest practical width, and 9 1/4″ is more common. Within the basic 24″ x 9 1/4″ dimensions, Label Innovation has manufactured some very small labels, including a set of tiny printed circles designed for sticking on the top of golf tees.