Basics

Paint with a ferromagnetic material, such as iron, mixed in
Allows for magnets to stick to the surface (granted it tends to be "weaker" than somthing like a metal plate, so weak magnets may not work, but a neodyminium or other strong magnet definetly will
Main use case is providing a mounting option other than screws or tacks for most applications (posters, small frames etc)
Can also be used for information boards etc
Can it be done diy (mix iron powder in paint etc?)
Can it be done with other liquid materials (epoxy, concrete)
Does it block rf etc (ie will it being used affect wifi coverage etc, by essentially making walls even more of a signal blocker)

Ferromagnetic Paint