I have done a few test of various filler and honestly regular wood filler (like Elmer's wood filler) was the worst and would come off with your fingernail (really okay for cabinet work only). The wood epoxy QuikWood, which is everyone's go-to favorite failed sooner than JB Kwikweld. I am not saying that JB Kwikweld was better than any other filler but it seemed to be the strongest to any of these: Elmers wood filler, Permatex Permaoxy Multimetal epoxy, Quickwood, Blue magic Quicksteel, JB wood weld epoxy.

I will try to post the results from the comparison test soon. I then simulated scoop hole wear spots on playfield like plywood. Then repaired the damage with various fillers and epoxies.

I then built jig (a 5ft pvc pipe with holes at every 6 inches, not at a 90 degree drop but about a 85 degrees) to drop a pinball from various heights which would focus a strike directly on the edge of the repair, I was looking for any type of chips or damage.

I was able to repeatedly drop a pinball on JB kwikweld at 5ft and it did not fail... Quikwood failed on the first attempt at 4.5 feet. So far JB Kwikweld has been the strongest (whack resistant!) of everything I have tested.... but my tests continue.

I have not yet tested bondo filler or bondo brand fiberglass filler, but I will soon and then post all the results.