The lo-fi (possibly the lowest fi) method I use is to rest my phone on a high table or desk with the camera end peeping out over the edge.
I stick my guitar vertically and adjust my position until what I need is in frame. Far from perfect but at least its a start.
The biggest problem with that is you can’t effectively take a slo-mo vid because you need to use the front camera (on an iPhone). There’s no way to monitor what the phone is “seeing”. At least no way that I know of.
One idea would be to get a small tripod like this, for easier, more consistent positioning:
https://smile.amazon.com/Manfrotto-MTPIXI-B-Universal-Smartphone-Adapter/dp/B0751J149H/
You could place on a chair or something and with a bit of testing you can probably get the framing right. Trickiest part may be locking in focus/exposure, for that you could try e.g. putting the guitar in a stand in a close approximation of where it’ll be when you’re playing, locking focus/exposure and hitting record, then getting back into playing position. Or if you could rope someone in to help start recording, even easier 
But just doing it by trial and error can certainly work.
THats exactly what I have. It does work but as you said, there’s a trial and error aspect.
So, I posted my first video yesterday using my own cheap ‘n’ cheerful Magnet alternative. Although I did actually by the plans for the magnet a while back the cost of getting someone to make the form for me killed the idea. I ended up making this alternative for exactly £0 as I had everything I needed lying around. It is far from perfect but it did the job this time. I plan to improve it slightly by jointing two clamps together to significantly improve the stability and will make the over hang below the clamp bar smaller to give better camera clearance.
I’ve got a few of those clamps around the house too!!
You can’t go wrong with those although they aren’t the most secure on their own. I plan to join two together for added stability later this week.
I made the big ugly wooden bit because the only magnet I had lying around was the mobile phone dashboard holder and needed a big hole. I plan to pickup some magnets with screw holes this week and mount them directly onto the clamp bar too. Should be a much better solution.
Cool. Let me know how well it sticks to the electric and if you think its stable enough for a heavier Galaxy Note phone.
Works great! Brilliant on the acoustic and works well on the electric. Only thing problem factor would be flat surface area on your guitars. Works fine on my superstrats but anything archtop or with a pickguard in the way won’t work. This one has a clamp that makes the suction really tight so I don’t see weight being an issue. There are probably a hundred of these clips on Amazon so I would measure your phone and see what’s out there.
Test clip on my San Dimas
Is this the one from the link above? I know there are a slew of these things out there.
Ill try and track down the link to what I got. The one in your first post looks like more of a cradle, like you’re supposed to use it to read music or tab while playing or something. Mine is more of a spring-loaded clamp. To hold your phone on the inside of your windshield for GPS while driving, sorta thing
ok, I got mine today. It works and suction isnt a problem with heavy phones. The only issue I have is that it bounces a lot when I pick up speed. Maybe that is just a problem with having a heavy phone, or maybe because my technique requires a lot of movement.
Maybe you’ll have better luck if you attach it to your desk and just turn it around so you get a down-the-neck view.
Hey guys I found a solution for under $10. A Dewalt clamp and two little clamps. It’s a bit fiddly getting the phone in the right place but then it works fine. Here is a pic.
Is that a magnetic base on there too?
It is. however, I have significantly simplified it since then. It is now just the clamp with the magnets attached directly. Less hassle and works even better.
I just took the magnets out of the phone mount because I didn’t have any others lying around but any two magnets should work fine. The Phone mount also has a little metal plate that goes inside your phone case for the magnets to stick to. Any piece of thin metal should work
Looks like the magnets are tall enough that the phone clears the trigger part of the clamp…
This is awesome. Do you think this would work for a heavier phone, like a Galaxy Note?
I don’t see why not. I suppose you might need slightly bigger magnets if anything but in principle it should be fine.
