Mike Caldwell, a 35-year-old software engineer, holds a 25 Bitcoin token at his shop in Sandy, Utah. Caldwell mints physical versions of bitcoins, cranking
Mike Caldwell, a 35-year-old software engineer, holds a 25 Bitcoin token at his shop in Sandy, Utah. Caldwell mints physical versions of bitcoins, cranking out homemade tokens with codes protected by tamper-proof holographic seals, a retro-futuristic kind of prepaid cash. (Rick Bowmer/Associated Press)