A rubber duck from a store is vinyl. A printed collectible duck is whatever filament you load. The material changes the shine, the strength of the bill, and how obvious the layers are.
PLA
PLA is the default for display figures. It prints at modest temperatures, holds small features, and comes in the colors character ducks need. It softens in a hot car and it is not a bath toy. For a shelf piece, that is usually acceptable. Say so in the listing if you sell it.
Dry PLA still prints better than PLA that has sat open for months. A sealed bag with desiccant is the whole storage plan.
Matte and silk
Matte PLA hides layer lines and looks closer to a painted toy. Silk PLA catches light and can make a simple yellow body look closer to a classic rubber duck. Both can be fussier about temperature and stringing. Print a beak-sized test before you commit a whole character to a new brand of silk.
PETG
PETG is tougher and a bit more heat tolerant. It can string, and the surface is often glossier than people want on a face. Use it when the duck will be handled, or when a thin prop keeps snapping. It is a poor match if your goal is a soft matte costume.
What not to assume
“Rubber” in the name of the product is the look, not the material. Do not sell a PLA duck as silicone, vinyl, or food-safe because the shape is a duck. If you have not tested a claim, leave it out.
Support material and soluble supports are a separate purchase. Many small ducks can be oriented to reduce supports, but Duck Heroes is not promising that every future file will be support-free. Follow the note that ships with the file.
A practical spool set
If you print character ducks often, a useful starter set is a warm yellow, a black, a white, an orange for bills, and one accent. Exact brands change. The habit does not: keep them dry, and reprint your temperature tower when you change brands. Color choices are in filament colors.
Pair the material with a machine that can hold a small first layer. Choosing a printer is the other half of this decision.