I pasted the monkey upon the thinking man, flipped it horisontal, adjusted it to fit to the human body.
I removed everything but the monkey face with a layer mask.
step 2 of 5
I used a clipping mask to select the monkey arm.
step 3 of 5
I pasted the arm on the canvas, flipped, rotated and adjusted the size to make it fit to the man.
step 4 of 5
The original image of the man has a lot of noise, so to match that I added noise (10 % gaussian noise) to the monkey and arm layer
step 5 of 5
I duplicated the monkey face layer and the arm layer and made the duplications 50 % desaturated with a hue/saturation adjustment layer. To these layers I also added the cyanotype filter in the same adjustmant layer. In the end I made these layers 40 % opaque.