Legal Question in Personal Injury in Nevada

Yes. It does not matter (for anything) if something is for "collection purposes." If its illegal, its illegal for collection purposes. As to plastic, it refers to metal so they may not violate that law. The problem if you use them for intimidation you may be in violation of many other laws and subject yourself to lawsuits.

The specific statute from Nevada law:

NRS 202.350:

1. Except as otherwise provided in this section and NRS 202.355 and 202.3653 to 202.369, inclusive, a person within this State shall not:

(a) Manufacture or cause to be manufactured, or import into the State, or keep, offer or expose for sale, or give, lend or possess any knife which is made an integral part of a belt buckle or any instrument or weapon of the kind commonly known as a switchblade knife, blackjack, slungshot, billy, sand-club, sandbag or metal knuckles . . .

A first offense is a gross misdemeanor (minimum 1 year in jail and up to $2,000 fine), and a subsequent conviction is a category D felony and shall be punished as provided in NRS 193.130 (1-4 years in prison and up to $5,000 fine).

Brass Knuckles are illegal in Nevada. Using weapons to 'collect' is illegal. You need to become familiar with the FDCPA before you go out collecting, or even trick or treating.