When the frame was finished, it remained only to hang the picture.
Fortunately I have metal door frames in my flat so I could use two S-20-10-N-Magnets
One was glued to the back fo the frame, the other could be placed without glue on the metal door frame.
So that it wouldn't slide to the floor, I placed a bit of double-sided tape at the right height.
This would allow me to move the puzzle to another place without any trouble, if only these magnets weren't so strong and therefore difficult to remove from the door frame! ;-) With a small bit of cardboard glued on the top of one magnets, you can protect the frame from crashing too hard into the door magnet.