I was wondering this too until yesterday!
Just been given a stack of sheet-lead from a friendly builder. I've taken one or two bits and rolled/bashed them into 1" thick 1ft long cigar-shapes and gonna cut these into lengths which'll weigh 4-10 oz. Thought I'd then simply drill a hole through each one and thread 50lb mono through and tie this into a loop. Should be ideal for casting up to 50m - nothing too heavy! - on deepwater snaggy rock-marks with a rotten bottom rig, or even without if very close-in, and such little effort is involved that they are worth nowt each in terms of time taken.
You could always do similar if you can get hold of some old lead piping - just cut up to required weight, drill and thread the mono through.
Cheers - John