A mobile device mounting system includes a device case and a mount. The device case includes: an insert including a rectangular bore and defining a set of undercut sections about the rectangular bore; and a first set of magnetic elements arranged in a first pattern about the rectangular bore. The mount includes: a body; a polygonal boss extending from the body and configured to insert into the rectangular bore; a set of locking jaws arranged on the polygonal boss configured to transiently mate with the set of undercut sections to constrain the polygonal boss within the rectangular bore; and a second set of magnetic elements arranged in a second pattern about the polygonal boss and configured to transiently couple to the first set of magnetic elements to transiently retain the mount against the device case and to drive the set of locking jaws toward the set of undercut sections.