Painted on wood boxes.
The back site of the boxes/paintings are numbered and signed, hardware is installed to safely mount this work on the wall.
I have also added a technical drawing with a number of possibilities how to hang the work in different combinations on your wall.
The work is expressly intended to be placed in the combination of 4 pieces, since the four separate parts represent one portrait
in my opinion .
PS The photos are taken in daylight (during winter), this explains the small difference in color temperature between the photos.