The actual making of a Paul-Son chip is not what the average person can do. They would be very costly to make.
Most counterfeits are altered chips.
Get a $1 and make a $100 out of it.
At the FQ's in 1996 we cashed about a dozen before someone noticed them. We caught the guy trying to get number 13 cashed.

The Palms had their B&G $100's counterfeited. They had Chipco sized 39MM blanks. Computer generated inlays and pasted them on. Cashier noticed they were 1MM smaller than ours. Caught him getting number 6 cashed.

I did see counterfeit $100's from a CA indian casino. They were altered chips

That said, Maccau has had at least twice been counterfeited for over 1 million, once with RFID chips. I never saw them so can't comment on them.

Most casinos know who has their $500 and ups. Makes it harder to get them down.