The 170° fisheye lens on the HDR-AS30V action camera protrudes from the front of the case, the better to view the passing scenery:
Unfortunately, that means there’s nothing to protect it when the scenery gets a bit too close.
Mounting it upside-down in the skeleton frame provides a bit of protection, by putting it inside the straight line connecting the helmet brim with the top of the frame:
That won’t protect it from severe impacts, but perhaps a casual drop won’t scar the lens. You can tell from the scuffs that the helmet does get dropped every now and then.
Most of the camera mounts on Thingiverse don’t take that into account, alas.
When you remove the skeleton mount from the helmet, grip the camera between finger and thumb while releasing the latch with your other hand. The mount will dangle from your fingers and the camera won’t slide out; if you don’t have both hands free, don’t mess with the camera.
Even though it doesn’t look at all like a GoPro Hero, everybody recognizes the “camera on helmet” meme and, in general, behaves a bit more circumspectly. I didn’t see that coming, not at all.