Sticker sheets are one of the easiest ways to get more mileage out of a design you've already made, and they've become a genuinely strong seller in their own right — low price point, low buyer hesitation, and surprisingly good margins relative to the effort involved.
The simplest version: take a design that has multiple distinct elements (say, an illustration with a skull, a few smaller floral accents, and a bit of text), separate those elements into individual stickers, and arrange them together on one sheet. If your original design was built with layers in a vector editor, this is often just a matter of isolating and slightly resizing pieces you already have — no new art required.
Size and spacing matter more than people expect. Most print providers want at least a small gap (often 1/8 inch or more) between individual stickers on a sheet for clean die-cutting, and cramming too many elements onto one sheet makes it look cluttered rather than generous. A sheet of 6-10 well-spaced stickers usually reads as more premium than one crammed with 20 tiny elements.
Kiss-cut versus die-cut is worth understanding before you order. Kiss-cut stickers are cut through the sticker layer but not the backing paper, so the whole sheet peels off the backing as one piece and individual stickers get peeled off by the buyer — this is standard for most sticker sheets. Die-cut means each sticker is fully cut through, including the backing, so they're already separated. Sheets are almost always kiss-cut; individual standalone stickers are usually die-cut.
Where this gets genuinely useful for a small shop: if you're already producing a design as a shirt, that same art (or its individual pieces) can become a sticker sheet, a set of individual vinyl decals, a pin, and a phone case, all from the same original file. You're not creating four new designs — you're repackaging one design's assets into four different formats, which is a much faster way to expand a catalog than starting fresh every time.
If you're not sure where to start, pick your best-selling design first. It's already proven people like the art — turning it into a sticker sheet is close to free additional revenue from something you know works.