starting this thread to share methods of molding & casting 3D-printed parts.
silicone molding of PLA parts from FDM printer from Smooth-On:
how to on 'dump molding' from Tested. (SAFETY SPOILER ALERT: THIS GUY REALLY NEEDS TO BE WEARING GLOVES)
Informative video here on cold casting of metal powders with a polyester resin:
You can download his .STL files here, if you're into his robot heads...
And then this guy got real intense about it and actually cast aluminum in a homemade furnace. Yeah.
Sorry, this guy is just so hilarious I had to post his video too: