So, smartphones are great these days for many sophisticated tasks, but also for one particularly important one: they all have quite good torches! Now, you've already seen the photos, and you know where this is going, and you're thinking "won't I look like a fool, wearing a phone on my forehead?". Yes, yes you will. But, read on!
This is one of those ideas that seemed fun and a bit impractical, but managed to turn out legitimately useful. You can genuinely use your phone as a head torch, and it's actually pretty stable. All you need is two of these brackets, and some webbing or elastic. The idea is that with "buckles" at both the smartphone and behind your head, you can tighten a pair of straps firmly around the phone, to keep it secure, and then independently adjust the tension on your head.
Note that there are two models. The larger one is for bigger phones, and helps keep things steady, as tested on the Pixel XL in the photos. Note that you'll still probably want the regular sized one at the back of your head, regardless of which you use at the front.
NOTE: FOR NOW, THE LARGER MODEL HAS BEEN REMOVED! There's an issue with the level of complexity; hopefully I can restore it once it's sorted out with the Vectary people. In the meantime, the model is on MyMiniFactory, here: https://www.myminifactory.com/object/44568
Let's consider some technical points:
The model is made for 20mm straps, but you can of course just scale it to whatever you like.
The integrated buckles grip nicely if you weave them like you would on a bag strap. Try it, and you'll work it out.
In the photo of the rear buckle, you'll notice that the ends of the straps are hidden. If you want the ends available for easy tightening, just flip the buckle over so it faces outwards.
So, go forth and illuminate things, hands-free! Or, alternatively, use the thing as a point-of-view camera mount, or to secure your phone to inanimate objects!