Since roughly the time of the first Iron Man movie — and perhaps long before based on the comic book — people have been creating their own versions of Tony Stark’s Arc Reactor. While Stark (fictionally) assembled his first reactor in a cave using scraps, reactor replicas could be thought of as mini time capsules of the technology available to makers over the last decade.
Reactors made closer to the movie’s 2008 release seem to have used more of what was available and could be modified into the appropriate form. Builds today, however, like the excellent MK I model by LizardWizardGizzard, can take advantage of custom 3D-printed parts, tiny microcontroller boards, and addressable LEDs.
As seen in the sort clip below, this reactor does a startup sequence with blue lights when initialized. It then spins faster and faster until it turns into a solid “heartbeat," with the lights pulsing brighter and dimmer in unison. The outer lights are shown via a NeoPixel ring, while a single LED cut off a strip in the middle pulses with the outside when initialized.
The reactor is controlled by a DFRobot Beetle board, based on an ATmega32U4. The structure of the device, including diffusers for the LEDs, is mostly 3D-printed, with copper coils wrapped onto it by hand as appropriate. This reportedly took “ages to wind by hand,” but this ‘Gizzard would have added even more if there was room.