*moved to resources*
C4d's are abstract renders made in a program called cinema c4d.
There are normal c4ds which just look like a normal render. They look good added to sigs to fill in spaces. They look best set to lighten or normal.
Effect c4d's look a bit different and smoother looking and most of the render is filled with black. These c4d's are best set to linear and colour dodge.
You can find them on sites such as
PSD Protocol - With 5465 PSDs We Are The #1 PSD Resource and
GameRenders - Your Source For Free Gaming Renders