I used lead flashing on my Springer cut in to 3"x 1" strips in a pile each side, I use a couple of spots of pva glue between the strips this holds them firm but can be removed if needed ...
That's exactly what I did for #1 Springer, but I was up against a lack of space with #2 on account of a different battery layout.
What I needed was lead ingots. I had the lead flashing offcuts, the camping gas stove and the blowlamp to heat it up in an old pan with, but I couldn't for the life of me think of anything at all to use as a mould.
Then I found an old brick in which the frog was formed in two halves. Couple of hours on top of the woodburner to make sure it was bone dry, and Bob's yer mother's brother. Nice rectangular chunks of lead about 10mm thick, each weighing 400gm
Btw, have you seen how far the price of lead has dropped in the last few years? Definitely not worth climbing about on church roofs now ...