Step 1 : print the model
Step 2 : on the picture, draw a grid with equal squares
Step 3 : on the back side, number the squares left to right
Step 4 : cut the little squares
Step 5 : prepare square papers with numbers on the back side, to replicate the drawing of the model
Step 6 : gather your squares together
Step 7 : you can fix it on your wall !
Details : http://kidworldcitizen.org/2014/03/23/diego-rivera-for-kids-make-your-own-mural/