Overview
Most items can be sold on eBay, but certain categories are restricted (extra conditions apply) or completely banned, based on legal requirements and marketplace safety. This is entirely eBay's call - 3Dsellers doesn't decide what can or can't be listed, and can't override an eBay block on a restricted category.
Broad categories covered
eBay maintains individual policies for dozens of specific categories, including (not exhaustive): adult items, alcohol, animal products, art, firearms & accessories, replica/toy weapons, knives, hazardous materials, human body parts, illegal drugs & paraphernalia, medical devices, military items, prescription/OTC drugs, real estate, stocks & securities, tobacco & e-cigarettes, used clothing, vehicles/parts, and virtual currency - along with cross-cutting rules like counterfeit items, stolen property, price gouging, and international trading restrictions.
Because this list is long and each category has its own specific rules, the fastest way to check a specific item is to search eBay's full list directly rather than guess.
General rules that apply across categories
The item must comply with all applicable local, state, and national laws - not just eBay's own policy
Something legal in the seller's country may still be restricted for buyers in another country - see eBay's international trading policy for cross-border sales
Listings that don't comply can be hidden until fixed, or removed entirely, with an explanation sent to the seller
Is this an eBay restriction or a 3Dsellers issue?
eBay-side: a listing was removed or hidden specifically citing a prohibited/restricted item policy; an item can't be listed at all in a certain category or to certain destinations; a category requires a certification or extra info eBay itself demands before allowing the listing.
3Dsellers-side: a listing was accidentally miscategorized by a bulk import or automation in a way that triggered an eBay restriction that wouldn't otherwise apply; a category mapping error caused an item to be placed in a restricted category it doesn't actually belong in.
Tip: if a seller reports a listing being blocked for a "prohibited item" reason, check the actual eBay category and item specifics first - a wrong category assignment (including one caused by a mapping or import issue) can trigger a restriction that wouldn't apply to the correct category.