Looked and couldn't find something like this so I mixed one up. The magnets are necessary for this mount. Print as many links as you need.
I made both a center ball and a corner ball to fit various circumstances.
Thanks to Zach Freedman for the Gridfinity system, @mkoistinen for the flexi arm, and @tevashkevich for the c270 mount.
The author remixed this model.
Added ball to a magnetic lid from the Gridfinity system by Zach Freedman (https://thangs.com/designer/ZackFreedman)