You won't have any sonic issues with no hollowing, just a heavier cup. For sanding I started with a more coarse sandpaper and sanded it down, then did a light acetone wash, then smoothed it out with a lighter sandpaper. I then did a coat or two with a spray primer, then did several light coats with spray. First set I did a rustoleum hammered which looked pretty good, 2nd set used a red caliper paint which had more sheen. Lastly I used a clear gloss spray on it to give it a clear coat. Be very careful not to infill the little bass holes if you're spray painting; make sure to clean them out after each round, otherwise you'll have to take a thin nail and open up the holes at the end (a pain!).