@Sean Seena posted:@IaM-Ray You're probably familiar, but rare earth magnets are insanely strong. Scary strong. So strong that you sort of have to be careful while working with them. If you stop being mindful, 2 will crash together. That's what happened with this double stack in the photo (notice the others have spacers that they came with, even with these spacers they're hard to peel apart). I think I may never be able to separate those two...
Speaking of, they will amplify the magnetic force when "in series." With diminishing returns as you add more. This is good to know because you could mount 2- or 3-stack behind the fiberglass if you're wanting more force. The ones I linked come with more than you'll ever need.
It's hard to demonstrate how strong they are, but here's a video with 1 magnet behind the fiberglass.
In terms of adhesion, I'm not sure. I may try some double-sided gorilla tape I have for one behind the fiberglass, and one to an extra phone case I'll leave in the car. Or maybe even better is a low profile pincher phone mount is connected to the outer magnet. Like these but with the back part flat.
Couldn't you just use a small piece of metal attached to the phone case so there is only one magnet in this equation? Similar to a Scosche Magic Mount pad?