"For Mark, and many of us, the goal is to remove the antiseptic sting of a clean 3D render. If the goal is to make a computer painting that looks like an oil painting or watercolor there are many programs and techniques for getting there. And as you mentioned above, not surprisingly, they require painting!  : )"

I don't necessarily agree. Much of removing that clean, antiseptic render look from 3D is choosing the right textures. You won't find too many clean renders in my art. Several years ago I was taught a principle called level of detail by a professional CG guy. No, that doesn't mean how much detail you put in. In means nothing in life is clean. It means breaking up specularity, showing the dirt and grime and wear of life.

As well, having lived in Japan back in the 70s, I became a believer in a principle called Sabi. There are actually three principles, wabi, sabi and suki, but I concentrate mostly on sabi, which is Beauty that treasures the passage of time, echoing the original meaning of the word: rust or patina. Objects or constructions created from organic materials and used in daily life are of course beautiful when they are brand new. But sabi describes the new and different phases of beauty that evolve in the course of their use and enjoyment, and the conviction that the aesthetic values of things is not diminished by time, but enhanced. The wear and tear of daily use, lovingly repaired and attended to, does not detract, but adds new beauty and aesthetic depth. Indeed, sabi is at its ultimate when age and wear bring a new thing to the very threshold of its demise. Appreciation of sabi confirms the natural cycle of organic life – that what is created from the earth finally returns to the earth and that nothing is ever complete. Sabi is true to the natural cycle of birth and rebirth.

Using sabi and level of detail helps remove the clean from 3D.

I've also seen many 4D renders by artists far more advanced than I, in which they have used painted textures to create painterly renders which range from cartoon like simplicity all the way to old masters funn paint. I've seen re4nders that are basically copies of old master painting where it's hard to tell the difference. And most of these were not estensivey post worked.

Painterly renders can be done in 3D. It takes high skill in texturing, modeling, lighting, composition, all the skills we're all working to develop anyway. No, I haven't done it. My modeling and lighting skills aren't there yet. Plus, I'm an illustrator, so I do what I do the way i do it. Though i admit to wishing I had the knowledge and skill to create cartoon like renders. But a lot of that is in the modeling and I haven't grasped the concept yet.

As far as using scripts or filters in post work, I do. But I gernerally use several layers, several different filters, manipulation and various types of blending. If you look at my series of fairy paintings, you can see I do create painting type illustrations, but they all have my really weird over staurated and bright colored look to them. Done with multiple filters and layers and blending and manipulation. A hell of a lot of work, in other words.

But don't blame 3D for non painterly renders. It can do the job, but only if you have the patience and skills to do the work.

I would also suggest that in order to learn more about painterly techniques, study matte painting a bit. Those folks are amazing at what they do.

Talent is God's gift to you. Using it is your gift to God.