I made an Oak mold board with a series of 1/2" holes and some 1/2" dowel plugs to hold the lead from leaking.
Tap them in about a 3/8" with a hammer.
Carefully pour the lead into the holes. Better not to fill to the top. I used a 1/2" pin to drive the cylinders out from the bottom even face. It worked ok, a couple tops got damaged and a few mushroomed enough to make removal harder. I noticed when I first poured the lead in, that it boiled up. HUH! Yeah, the wood was wet and the steam bubbled up through the molten lead, thus those cute tops. I would leave about 1/4" from full. Yeah, there was some uncontrolled fills on my part, too
The block will spend the night in the food dehydrator and hopefully no more blown lead.
This is the bottom, nice even surface to drive the cylinders out with the matching 1/2" drive pin. LET the lead cool well before driving it. You want to avoid mushrooming. Harder to remove and I cut off the mushroom to even out the roller diameter. There is no waste, the scrap goes back in the pot.
The cleanup. Note how the drive pin mushroomed the top of the 2 top long rollers. Some of the short pieces resulted from a double pour, no bond, don't do it, the too short cylinders tumble not roll. I watched the action in the mill to see what was rolling and what wasn't. Interesting that they seem to be a little different diams.
And a half hour or so roll in the ball mill. Not perfect but they roll like crazy in the mill. The next batch will be better, No steam pressure messing with the cylinder shape and hopefully the holes will be a little smoother from use. I put the 2 shortest ones (the tumblers) back in the remelt pot.
I'll try another batch or two tomorrow and we'll see how it goes.