Made a simple hook with 2 embedded magnets inside. Just to hold my keys or the remote for the window  stores. 
Put it on the fridge or metal memmoboard.

Magnets are 10 mm by 3 mm tall.
2 walls

15% infill 
Printed with a .6 nozzle

Layerheight at .18 mm

Pauze is inserted at layer 19 

No support needed

No specific filament needed, pla, pla+, petg, … anything will do.