I spent a couple of hours researching metal that is soft like lead, has no toxicity and won't tarnish.
Geezer came very close to hitting the nail on the head when he suggested Pewter. I also found a company selling a tarnish free tin based sterling replacement, which was a great hint. I also did a lot of research into which metals tarnish, oxidize or other similar terms.
The short answer is that a certain type of Pewter should fit the bill. Here is a link to a seller, Rotometals.
https://www.rotometals.com/pewter-alloys/
They have three pewter alloys. Copper tarnishes. As it turns out, pure silver doesn't tarnish. Traditional Sterling, which has 7.5% copper tarnishes because of the copper.
One of the alloys they have, R92, has no copper. I ordered an ingot of that. One of their videos mentions that the A/C pewter is more malleable after casting, so I got an ingot of that as well. It is only .25% copper, thus I'm hoping that tarnish won't be a big deal.
I'll report back on these materials once I've actually used them.
Next, several have asked about using solder. I have used this. My hammering hand has been giving me trouble, so I melted it. I did have a few issues with it, though think those are because I haven't learned how to be effective in melting. I was able to produce nice wedges with the solder.
Finally, there is a type of Sterling Silver, called Argentium Silver, that doesn't tarnish. I want to try that one of these days. I couldn't find a sheet thick enough to work, thus it would require melting it.
The issue with melting it is that unlike lead and pewter, it takes very high temperature to melt silver.
I thought some folks may find it helpful and wanted to share.