Regarding your concerns about pouring molten pewter - drip some solder onto a piece of thin card (on a heat-resistant surface). See how big the blob needs to be to burn through.
You could use some sheet copper to back up the card or tape to act as a heatsink too, but I think that might be overkill.

It'll be interesting to see if you get a response on the woodworking forum; as you say, it's quite an old thread.