This is an easy to do project, and I wonder why a commercial equivalent has not alread been made. But leave it to me to come up with an idea like this. I call this project a "Mag-Pod", as it is a "magnetic tripod", or more accurately - a magnetic camera mount that may replace a tripod.
My intended use of this 'pod is when you are on your balcony on a cruise ship, and you want a stable platform to take a time-lapse video, or just take a few photos. Now you have a good excuse to book a balcony rather than an inside stateroom!
The 'pod consists of two commercially available products; a 100lb retrieval magnet and a 7" magic arm. It can be assembled in less than 5 minutes, and requires no drilling. The only tools you need a method of tightening a 1/4-20 nut. This can be a pair of pliers, wrench, or socket set.
The retrieval magnet comes with a hole already drilled for the magic arm, and even includes the 1/4-20 nut.
The magic arm has a 1/4-20 screw on each end, and either end is identical.
Simply unscrew the hot-shoe adapter from the magic arm, then put the screw into the hole in the magnet. Then attach the bolt, tighten it down, and you are done.
Since the Mag-Pod will find use on board a cruise ship, I had some concern that a 100lb magnet might mess with the x-ray machine as you go through check in. You don't want to get into trouble by breaking the x-ray machine as you board. I did contact the manufacturer of the magnet, and they assured me this would not happen.
One nice feature of the retrieval magnet - and one reason I chose this particular model, is that it has a set of plates that go over the magnets, which I understand more or less de-activate the magnet.
While the Mag-Pod is useful for a mirrorless and compact camera, or perhaps a video camera, I did try it with a 5lb DSLR.
The magnet held the DSLR well enough, but the magic arm was a bit wobbly, and the smallest vibration would probably be amplified by the arm. Still, this was a useful test to see how much weight the Mag-Pod would hold. I suppose you could make a "super-size" version by using a Manfrotto Magic Arm and a heftier retrievel magnet, but my needs are met with the smaller version I made.
Holding a 5lb DSLR.