Headloupe hook (fix for headloupe)

Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:3250533.

The screws on my headloupe always get loose by themself so the part with the optics goes down way too far. So I designed this little hook to keep the glasses always in the correct position. Easy print and simply clip on the loupe - no further modifications required.