It's legal to possess marijuana paraphernalia in California--but not because of the marijuana legalization law Proposition 64.
In fact, California's possession of drug paraphernalia law (Health and Safety Code 11364 HS) never applied to paraphernalia for smoking marijuana (such as bongs and papers for rolling joints).
The major forms of paraphernalia that are covered under HS 11364 include items used for smoking or injecting drugs like methamphetamine, cocaine and heroin.
And California's drug paraphernalia law now even makes an exception for syringes and hypodermic needles that are acquired from a safe, legal source like a pharmacy or needle/syringe exchange. This exception is in effect until 2021 and is designed to help prevent the transmission of needle-borne diseases among users of injected drugs.
The upshot is that, these days, California's drug paraphernalia possession law is applied mostly to items like miniature cocaine spoons and methamphetamine pipes.