RestEasy open-source chin rest for psychophysics

An open-souce chin rest design for stabilizing the head position of human participants in psychophysical behavioural experiments. More details [here](https://github.com/MonkeyGone2Heaven/SCNI_Toolbar/wiki/RestEasy:-An-open-source-chin-rest-for-human-psychophysics-experiments).

This design is a work in progress. It is designed in the excellent open-source CAD software [FreeCAD](https://www.freecadweb.org/), and the .FCStd file will be included here if you wish to make your own changes.