Does a "paint-able" putty exist?

Mr Surfacer 500 in the jar is great stuff,brush it in and sand it or remove it with alcohol on a Q-tip

Agree, Mr Surfacer 500, but you have to work real fast because it dries real fast. Experiment though. It is not good for large gaps, but fill small gaps well and levels quite well also.

Almost any of the solvent putties can be thinned with lacquer thinner and then applied with a brush.  Just be sure to clean the brush out immediately after!  Mix to a syrup-like consistancy.

Thank you kindly for the tips. And I was wrong, I was using Testors Contour Putty. But I can add/use ModelMaster Airbrush Thinner to it and make it "paint able", or do I need something else to thin with?

Try it- do some experiments.  My guess is that MM thinner is mineral spirits (turpentine) and you may need something stronger.  Lacquer thinner is a very strong solvent. In fact, do not thin too far or you risk damaging the model surface when you apply it.

I took some of the Testors putty, applied MM thinner until it was the consistency of syrup, and painted it on some test parts. It dried nicely with no seeming damage to the underlying plastic. I tried on some figures, then on some interiour seams of a test kit. Again, no issues. I'm liking the results and how it handles on the brush.