I experiment around with ALL the technologies for coating found in these forums and have settled on the ES gun application for speed, repeatability, low cost, and just plain easy to do.
But......I have tried several brands of spray-on epoxies, including VHT, and have found ALL of them work best when baked per the instructions on the cans. Without baking: 1) it may take DAYS for the stuff to dry completely hard, 2) the molecular bond chains do not form properly, 3) usually the stuff will scrape off easily even after setting for a week.
So, the chemical formulations are based upon baking. Unfortunately, those times are MUCH longer than the short 10 minutes it takes for PERFECT powder coating. And the spray cans cost a whole lot more per boolit than powder coating.
Hope you can find powder around where you are!
Good luck.
bangerjim