How can I recolor this 3d render with a good skin tone in photoshop cc? I tried but it was not convincing.
Usually you can do that quick+dirty (color balance or gradient map + some color/overlay layers) — but in this case it's quite obvious that the image was overlayed; or more slowly with lots of masks, overpaints and adjustment layers — takes more time but the result is more realistic: depends on your end goal.
My usual approach is like this:
I first create a base color gradient map
Then add a Posterize adjustment layer to get some color variation:
Then I try to fix usual 3d's too much contrast
Then Color and Multiply/Overlay layers, using a soft brush with low opacity I paint the areas that I think have to have different tones (nose/cheecks/fingers..)
And then on normal layer I add more color variations
So i end up with something like this.
I guess Photoshop's 3D is out of the question, you haven't access to the parts separately.
You can do ordinary 2D colorings in a simple way. That's done by making patiently very accurate selections and filling those selections with colors in new layers which have blending mode "color". The grayscale image gives the light variations.
One selection - one fill color is the easiest version. If you can imagine more complex colorings such as human skin, which has definitely different color nearly everywhere, you can paint much more than single color fills.
I made a selection with polygonal lasso tool and filled a little area in a new layer with a light reddish color. The selection covers only his hammer holding hand.
The job would be easier, if one makes a top layer which contains only the current colored metal parts. They could in theory be selected by color. Unfortunately your image has so bad color noise that seemingly grey parts actually are full of color. I tried to force low chroma values to zero chroma in Lab mode, but that greyed also much metal parts. An image which has never been JPG would be useful.