These stacklights would make great indicators for a printer as they only require a usb connection and from that you can get up to 5 lights and a buzzer. They appear as a HID device.
I've looked into how to get one of these working with Octoprint but it's beyond my very limited knowledge. Would someone be interested in taking this on? Lights are readily available cheap in the usual places and the manufacturers website has example python code and a manual with a description of what information to send to the device.
appears it's controllable via simple executable. if so, then you could use event manager (bundled plugin), or gcode system commands plugin, to control.