I had to do a massive powdercoating job today for one of my friends, but I did get a few hours of time for my own stuff.
The old gas tank was cruddy inside and had barnacles floating around inside of it. So, I flushed it real thoroughly with water/ muriatic acid mix to get all the gunk out. Then, scrubbed the outside extensively with acid and a scotchrite to get it ready for powdercoating. It's outside in the oven right now cooking for a few hours to make sure it's free of all acid and water.
This kind of project is pure joy for me. I can't get enough of it. I just wish it didn't get dark so I could work more hours in a day.