Action camera chin mount for the new RPHA 12 from HJC.
You will need a “j-hook” like this or something similar, as well as adhesive to stick it to the helmet.
I have ordered this set from Amazon since it contains everything that I needed.
I recommend ASA or PETG.
I made the mount/baseplate by 3D scanning the front of the helmet and then simply designed the baseplate in fusion 360 and cut it with the surface from the scan.