The original goal for the Fidget Cube Kickstarter was $15,000. It had raised around $1.5 million by the time I contacted the hardware’s inventor to ask how they were dealing with the sudden success.

When Antsy Labs introduced the Fidget Cube on Kickstarter last year, it found it had a hit. The product, which aims to calm users by offering various tactile features that spin, roll and click, raised ...