We haven’t tried these ourselves, but [3D Printing Nerd] has an interesting video review you can see below. We assume the ruby — which is just aluminum oxide — is lab-created and not a ...

The result is a bit like a plus-sized 3D-printing pen, but much simpler and capable of much heavier extrusion. But it wasn’t quite as simple as shoving scrap PLA into a hot glue gun and mashing ...