Nope, no Arduino involved! The original Form 1 and 1+ used an STM32F103. Some of the firmware used libmaple [1], which exposes an Arduino-ish API, but most of

Nope, no Arduino involved! The original Form 1 and 1+ used an STM32F103. Some of the firmware used libmaple [1], which exposes an Arduino-ish API, but most of the code was low-level C and C++. (I'm an electrical engineer at Formlabs, and was around through the Form 1+ product cycle) [1] https://github.com/leaflabs/libmaple https://github.com/leaflabs/libmaple