Typically, when I bring a board in for ding repair (edited to clarify: multiple dings) I finish up by sanding the whole board, then rolling a thin coat of epoxy resin. I don't stop rolling until the resin gels up and gets too tacky to keep rolling. The foam rollers cost about a buck apiece, and I will toss it after I finish rolling.
The video is not too exciting, but I wanted to show how very little resin is used for this final coat, just a little salsa cup full - same process I use when finishing up a glassing job with epoxy resin.
Once it dries I will wetsand starting at 320, and finish to whatever degree I feel motivated.
The board is 4 years old, and its got a little mileage on it, as a daily driver in often crowded L.A. conditions. The classic density foam from US Blanks is pretty tough, but collisions, rocks, etc. take their toll.