What is it?

Well simply put its a 80x80x4.5 square that when printed you can put Neodymium magnets in and then mount it to a wall using command strips and use to hang Steelbooks to.

Links;

Magnets; 30 x 10 x 3 mm Neodymium Magnets

Warning;

I am still getting used to modelling in blender and when I exported the model and put it into Cura it made the model 100000% bigger. In Cura the model has to be 80x80x4.5. I do aplogise if this gives anyone headaches.

That's pretty much it. I used command strips to mount the squares to the walls, you can use any filament you want, I used White PLA. From the images you can see that I even made a fully encased one but found that it was too weak to actually hold anything, hence the exposed magnets.