Face shield, Prusa specs

I made a design, based on the general dimensions of the [Prusa R3 one](https://www.prusaprinters.org/prints/25857) but made in such a way that no infill was required - everything is perimeters. Print using the settings in the screenshot - main thing is the 0.6mm extrusion width and a lot of perimeters.
Later I tuned the design in FreeCAD file so to be able to easy tweak basic dimensions and produce a headband tuned to persons head. The Face Shield Prusa R3_135mm.FCStd files is the later one. Shield_135mm_PrusaR3_kiss.stl is one such example tuned for a small kid. Kids model is generated with [Makehuman](http://www.makehumancommunity.org/).