In short, Go Green.
The picture shows the result of my experiment in casting a solder ingot: inside the mould its says "instructables" but sadly, solder does not take details very well.
The movie shows the process: the loose solder in a stainless steel dish is heated and stirred with a hot (50W) soldering iron, and then poured into the mould.
I have gotten into the habit of saving all the solder that comes my way, and I keep a receptacle (with lid) on my table for this purpose. When it gets to a respectable amount it is cast into some shape and stored. Some day I might attempt making a really big sculpture with reclaimed solder.
Lead is not poisonous. The compounds of lead are, however. If you keep all the lead containing alloy that comes your way as the metal, in some pleasant shape, cast or sculpted into some form that is pleasant to the eye, you will be helping the environment by keeping at least some of its potential pollutants at bay.
Start saving your solder today. Read on to find out how.