Lightfield Display
Another type of glasses-free 3D display.
This is a technique called integral imaging - it uses an array of little lenses to direct views of the scene in multiple directions.
I made the array by taking a mould from the front surface of a projector's collimating lens. There's a running theme of commenters urging me to put my devices in a vacuum - this lens would certainly have been improved by degassing the resin in a vacuum.
The image is being generated using https://shadertoy.com. The code creates a grid of hundreds of little renders of the 3D scene, pre-distorted so that the lenslet array can convert them into directional views.
There's the usual problem of demonstrating a 3D display using a 2D video so I swing the camera around to give a sense of parallax. The view cone is limited, and as the camera moves beyond it the image abruptly shifts back to the start.