you have to put some effect on a layer above the render... because i see the fully red joints... and a dark red on the bg...
1) duplicate the render
2) desaturate one and set to lighten or darken.. and lower opacity
3)create a layer
4) image->apply image
5) filter->stylize->extrude->press ok
6) put it to lighten and erase the partson the render
7) apply image
filter->sharpen->sharpen