CryptoPrinting.com, for example, will 3-D–print custom designs for prices the company claims are about 20 percent cheaper than its competitors'. Bitcoinstore.com offers a wide variety of electronic parts, such as Arduino microcontrollers, power supplies, and cameras. Go to Spendbitcoins.com for a list of other sites that take part in the blossoming mini economy, including virtual marketplaces like Coingig.com, where bitcoin owners can independently buy and sell items from one another.