Printed on the surface
Glitter print is a design cut or printed from a specialty vinyl and heat-pressed onto the item. The material is what you are buying: it brings a physical property — height, sparkle, shine — that no flat ink can imitate, and none of it shows in a flat on-screen preview. The surface is dense with fine reflective flecks that sparkle as the item moves, which is why it reads so differently in the hand than on a screen.
The glitter vinyl is a sheet material. A blade cuts your design out of it, the surrounding waste is pulled away by hand — a step called weeding — and what is left is pressed onto the item. Nothing is printed, so the finish is uniform across the whole design and every part of it is the same colour.
That process is what sets the minimums. A stroke thinner than 21 px (1.8 mm) tears as the blade passes through it, and a gap narrower than 18 px (1.5 mm) cannot be picked out by hand without lifting the parts you wanted to keep.
Weeding is the constraint most designs run into. Every enclosed space in your artwork — the middle of an O, the gap inside an A, the space between two tight letters — has to be removed individually. Small counters and tight interletter spacing turn a two-minute job into a fiddly one and raise the odds of a torn edge.
Text at 77 px (6.5 mm) or taller in a medium-to-bold face weeds reliably. Below that, or in a fine face with delicate counters, the internal shapes stop surviving the process.

Because the design is cut from a single sheet, the whole of it is the same glitter vinyl. Multi-colour artwork, gradients and photographs are not what this method does — it does one bold shape, or one line of lettering, in a finish that catches light in a way flat ink never will.
Designs that lean into that read best: a strong monogram, a piece of display lettering, a simple emblem. Complexity works against both the material and the eye.