Upcycled projection oscilloscope
This is an oscillscope that uses mechanical scanning mirrors and a laser diode. Mirrors are attached to the head arms of scavenged disk drives and driven with an audio amplifier. In the video, a UV laser is used and projected onto a glow-in-the-dark surface to give a similar effect as phosphor decay in an electronic oscilloscope.
In the video, the X and Y axes are driven with Lorentz Attractor code courtesy joshisanerd.com