Welcome!!
I think it is a great idea when smaller weight is needed. It is perfect for freshwater fishing.
The problem is with larger weights in saltwater. Sand is roughly 5-7 times less dense than lead. That means sand weights would be 5-7 times bigger than a lead weight. Which equates to a 8oz sand sinker the size of a cantelope. That is pretty impractical for this type of use!
There are many lead free weights on the market, that have a much closer density to lead. Bismuth, Tin, Copper and Iron have all been used. The best lead free metal for weight use is Tungsten...it is almost 2x's more dense than lead, which means heavier weights at half the size! The downfall to Tungsten is it is not a do it yourself metal. It's melting point is much higher than lead and could not be melted in a home melting pot. They do sell a Bismuth-Tin Alloy that melts at a lower temperature than lead, is easy to work with, is not much more expensive and is just about as dense as lead. Which means, you can use your old lead molds and get just about the same weight as with lead. The difference in weight lost is very minimal...they recommend you use heavier metal hardware.
Very interesting and good looking out for the children and the environment.
