[K7Sparky]

"I filled in one toggle switch hole on the side of a Philco tombstone model. I used some kind of plastic wood filler that dries as hard as a rock. It was advertised as being stonger than real wood, and I believe it. The problem with it, is that it doesn't take toner like real wood. This particular radio needed the sides and top refinished with extra dark walnut, almost an ebony look, so I was able to hide it well."

PuhPow - Sounds like you used Durhams Rock Hard Putty. Swells a bit as it dries and stays put great. As you said and as the can says stain the powder. Will not take stain. Used a bunch to fill screw holes on a cabin sole. Nice cream color and takes drilling to remove, but no way to stain.
I like the idea of doing a jagidy form patch on top of the dowel to help hide the patch.

Waiting for more ideas. I have trouble waiting to do repairs and have the paid the price too many times.