I just wanted to offer the following for your consideration and input:
I used to PC my boolits by putting them into a round Tupperware container (with the #5 recycling stamp on it) along with the powder and then swirling and shaking for about a minute. It worked, but especially after a number of batches using the same container, the PC would start looking very thin and splotchy. It took me a long time to realize that this was caused by the fact that the boolits were abrading the inside of the Tupperware so that little plastic shavings were adhering to the boolits along with the PC.
Lately I have been putting the boolits and powder inside a gallon Ziploc bag first, squeezing out most of the air, and then putting that inside the Tupperware container and swirling and shaking. I have also been adding another gallon Ziploc containing about 20 Styrofoam peanuts. This seems to help generate static electricity, but I haven't done any strict side-by-side comparison. Anyway, now I'm getting the best coverage I've ever had, with no more thin or splotchy appearance, and they shoot much cleaner as well. With the old method, I would end up with some residue on the inside of the barrel. It wasn't lead, and it would scrub out pretty easily, but it was kind of annoying. I now realize that it was probably residue from the plastic bits that rubbed off the Tupperware.
The only downside to this new method is that the boolits tear up the Ziploc bag after about two batches. If I could find some sort of material that could withstand getting battered by the boolits, that would be ideal, but for now I'm satisfied to use the Ziploc bags.
So, there it is. Maybe I've just reinvented the wheel, or maybe this will help someone. If you see any way I could improve on this method, please let me know!
John