Do you want photorealistic or symbol style? Many of the people at the Dundjinni forums use Daz to create their objects in 3D and render them

There was a lot of use of Deep Paint (version 2) but that produce no longer exists. (It used a 2.5D mode where you could set light locations and textures then draw stacked vector objects). Other than that any paint program can be used.

If you want mode icon/symbol shapes, a vector program like Illustrator or Inkscape is the better way to go.

-Rob A>