Note: This design is for the mount piece only, it relies on a purchased part for the MagSafe portion (see below).

I needed a MagSafe phone holder that would attach to my music stand. There are plenty of MagSafe holders to be found that rely on suction cups, sticky tape, clamps and other things to affix the base, but since I was attaching it to a metal stand what I really wanted was one that also used a magnet to stick down the base as well.

I found an inexpensive MagSafe holder online that attached to a small mount that was meant to be stuck down with 2-sided tape, and then redesigned the bottom mount section to use a magnet instead. I tried using one or more smaller magnets at first, but nothing held very well until the last one I finally tried. That magnet almost works too well, but it definitely holds the phone down securely.

In addition to printing the mount piece, you'll need the following parts:

• https://www.amazon.com/gp/product/B0CJNS28PW You'll just use the top MagSafe portion of the holder that the iPhone sticks to, and the adjustment nut. This was about $9 when I bought it. This also includes an adapter for a car vent attachment as a bonus.
• https://www.amazon.com/gp/product/B08HMGMXSH super strong magnets for the base. These were about $10 for 6, though you only need one. They can supposedly hold up 130lbs each! They're actually kind of hard to separate.

One the mount is printed, slide the magnet into the base, attach the top MagSafe top piece and nut, then tighten down the adjustment nut and you're good to go. The magnet should friction fit fine, though you might need to tap it lightly with a small hammer to make sure it's seated all the way. I think this turned out really well, it holds my phone in place rock solid, but also allows adjustments to the phone position by loosening the nut. Someday I might try to 3D print the top part as well, but for now this does what I need. Hope it's useful to you too!