In fact, there has since been a wide-array of other gold-type ETFs that have hit the market, like the iShares Gold Trust (NYSEArca: IAU) and the ETFS Physical Swiss Gold Shares ETF (NYSEArca: SGOL).
It is done using a special typeof liquid-crystal array developed by a British firm called Light Blue Optics, which is also developing the technology for use in tiny projectors (see article).