Thanks for the feedback guys, it's helpful not only for me but also for your fellow shooters. These dies are made by a caster for casters, and it's merely an interesting extension of my obscession...er, hobby.
gds, just let me know when you are ready, I'll be happy to fix you up. Ted, while it is possible to make a slotted die, I don't think it would be very workable. For one, it would take extra machining time, which would make the die more expensive. Two, the smallest mill I have is 1/8", which I think would allow way too much lube to flow through it, and you wouldn't be able to shut it off. This would probably be quite messy, and not very satisfactory. I'll try to make anything you ask for, but on experimental projects like this you are kinda on your own. A better solution would simply be to have a series of 4 or 5 closely spaced rows of holes, you can lube all the grooves in the tumble lube bullets cleanly this way. I have actually tried this, and it does work fine.
lathesmith