Over on Hackaday.io, [bms.had] is showing his technique for 3D printing molds that he uses to cast (lead-free) pewter objects. The process looks simple enough, and if you have a 3D printer, you only need some lead-free pewter, a cheap toaster oven, and PLA filament. He’s made two videos (below) that do an excellent job of showing the steps required.
Even though the pewter is hot enough to melt the PLA, it doesn’t appear to be a major problem if you quench the piece fast enough. According to [bms.had], a slower quench will melt some PLA although that creates a smoother surface. You can see the 0.31 mm layer lines in the cast, though, although you can use any layer height you like to control that. Creating the mold is simple (the videos use Tinkercad, although anything suitable for creating 3D models would work). You essentially attach a funnel to your part and make the entire part a hole inside an enveloping shape.
Once you print the mold and fill it with molten pewter, you quench it in water and then put the whole thing in a somewhat cooler oven. The PLA will melt before the pewter, making it easier to remove the piece from the mold. Of course, you destroy the mold during removal, but you can always print another one.
Pewter is mostly tin, with a few other metals added. We’ve talked about casting it before (including tips on how to recycle for a cheap source of pewter). The [bms.had] technique struck us as the opposite of what we usually see: PLA surrounded by investment and vaporized by molten metal. However, we have to say, we dig the cufflinks.