This motorcycle helmet mirror adapter is mounted on the side of the helmet and is designed to fit the following blind spot mirror (the oval one) ...
https://www.amazon.com/gp/product/B082F91C8M/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1
to a motorcycle helmet, with the use of a 4mm x 250mm (~10 inches) carbon fiber rod.
UPDATE 3/23/2024: I replaced my side mounted mirror with a chin mounted flat mirror, which provides a clearer view and isn't prone to vibrating when riding over bumps. The chin mounted mirror is posted at https://www.thingiverse.com/thing:6546807
base.stl | 501.0KB | |
elbow.stl | 1.1MB | |
helmet_mirror.stl | 741.7KB |