As seen from the previous picture, it was a bit messy to test ;-) - the next steps had to be a proper case (later printed in black for less internal reflections)... this would allow for more precise alignment and testing (distances etc.):

The upper part is switched to semi-transparent to have a better look inside... there are multiple mounting options to slide the display in (precisely the circuit board, so the screen would sit directly on the printed part).

The small case at the front will contain the thermal sensor, while the "window" will be covered by a magnifying lens. We used fresnel lenses (2 of them added) to achieve a good magnification. The mirror acrylic sheet will sit on the angled wall.

The sensor and display are now soldered to the Raspberry Pi Zero W:

So we finally had a good way to test the prototype - wearing it!