Check out this inspiring aluminum casting demo from 3DTopo that shows the practical process of using PLA for lost-wax casting methods, that they have dubbed “lost PLA casting”:
This page describes my first successful attempt casting aluminum parts directly from 3D printed PLA parts. The process is practically identical to lost wax, but instead of burning out the wax, I burned out the PLA plastic (which is a bio-plastic).
I needed some aluminum parts to mount my focusing lens for my 150W CO2 cutting laser. The parts needed to be adjustable, and I needed it to mount to some scrap extruded aluminum I had laying around.
I am absolutely thrilled about the possibility of going from concept -> design -> 3D Print -> finished metal casting all in the course of 1-day.