Slug on the right weighs 4.20 lbs, made from small diameter copper wire salvaged from fractional horse power electric motors.
A quick dip in a very dilute sulphuric acid would remove the oxides giving you a much cleaner looking slug, with copper sulphate as a by product. Any decent scrap yard that owns an XRF will gladly accept this as number one copper.
For those of you that sell copper bullion on ebay these copper slugs pack into a box really nice and compact. For every pair of slugs facing up another fits into the inverted space filling the gap.
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