A simple educational model demonstrating the principle of visual docking indicators used in spacecraft when docking in orbit - these are usually only used as a backup or additional indicatorusing parallax and the 3d shape you can see if you arealigned correctly, on track, rotated and how far away you arethere are varios designs for such docking targets - the model is based vaguely on the one used by soyuz spacecraft and designed to fit in a basic 3d printer and demonstrate the basic working principle of such indicators